CVE-2026-43080: l2tp: Drop large packets with UDP encap

Published May 6, 2026
·
Updated

In the Linux kernel, the following vulnerability has been resolved:

l2tp: Drop large packets with UDP encap

syzbot reported a WARN on my patch series [1]. The actual issue is an overflow of 16-bit UDP length field, and it exists in the upstream code. My series added a debug WARN with an overflow check that exposed the issue, that's why syzbot tripped on my patches, rather than on upstream code.

syzbot's repro:

r0 = socket$pppl2tp(0x18, 0x1, 0x1) r1 = socket$inet6udp(0xa, 0x2, 0x0) connect$inet6(r1, &(0x7f00000000c0)={0xa, 0x0, 0x0, @loopback, 0xfffffffc}, 0x1c) connect$pppl2tp(r0, &(0x7f0000000240)=@pppol2tpin6={0x18, 0x1, {0x0, r1, 0x4, 0x0, 0x0, 0x0, {0xa, 0x4e22, 0xffff, @ipv4={'\x00', '\xff\xff', @empty}}}}, 0x32) writev(r0, &(0x7f0000000080)=[{&(0x7f0000000000)="ee", 0x34000}], 0x1)

It basically sends an oversized (0x34000 bytes) PPPoL2TP packet with UDP encapsulation, and l2tpxmitcore doesn't check for overflows when it assigns the UDP length field. The value gets trimmed to 16 bites.

Add an overflow check that drops oversized packets and avoids sending packets with trimmed UDP length to the wire.

syzbot's stack trace (with my patch applied):

len >= 65536u WARNING: ./include/linux/udp.h:38 at udpsetlenshort include/linux/udp.h:38 [inline], CPU#1: syz.0.17/5957 WARNING: ./include/linux/udp.h:38 at l2tpxmitcore net/l2tp/l2tpcore.c:1293 [inline], CPU#1: syz.0.17/5957 WARNING: ./include/linux/udp.h:38 at l2tpxmitskb+0x1204/0x18d0 net/l2tp/l2tpcore.c:1327, CPU#1: syz.0.17/5957 Modules linked in: CPU: 1 UID: 0 PID: 5957 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 RIP: 0010:udpsetlenshort include/linux/udp.h:38 [inline] RIP: 0010:l2tpxmitcore net/l2tp/l2tpcore.c:1293 [inline] RIP: 0010:l2tpxmitskb+0x1204/0x18d0 net/l2tp/l2tpcore.c:1327 Code: 0f 0b 90 e9 21 f9 ff ff e8 e9 05 ec f6 90 0f 0b 90 e9 8d f9 ff ff e8 db 05 ec f6 90 0f 0b 90 e9 cc f9 ff ff e8 cd 05 ec f6 90 <0f> 0b 90 e9 de fa ff ff 44 89 f1 80 e1 07 80 c1 03 38 c1 0f 8c 4f RSP: 0018:ffffc90003d67878 EFLAGS: 00010293 RAX: ffffffff8ad985e3 RBX: ffff8881a6400090 RCX: ffff8881697f0000 RDX: 0000000000000000 RSI: 0000000000034010 RDI: 000000000000ffff RBP: dffffc0000000000 R08: 0000000000000003 R09: 0000000000000004 R10: dffffc0000000000 R11: fffff520007acf00 R12: ffff8881baf20900 R13: 0000000000034010 R14: ffff8881a640008e R15: ffff8881760f7000 FS: 000055557e81f500(0000) GS:ffff8882a9467000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000200000033000 CR3: 00000001612f4000 CR4: 00000000000006f0 Call Trace: <TASK> pppol2tpsendmsg+0x40a/0x5f0 net/l2tp/l2tpppp.c:302 socksendmsgnosec net/socket.c:727 [inline] socksendmsg net/socket.c:742 [inline] sockwriteiter+0x503/0x550 net/socket.c:1195 doiterreadvwritev+0x619/0x8c0 fs/readwrite.c:-1 vfswritev+0x33c/0x990 fs/readwrite.c:1059 dowritev+0x154/0x2e0 fs/readwrite.c:1105 dosyscallx64 arch/x86/entry/syscall64.c:63 [inline] dosyscall64+0x14d/0xf80 arch/x86/entry/syscall64.c:94 entrySYSCALL64afterhwframe+0x77/0x7f RIP: 0033:0x7f636479c629 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffffd4241c8 EFLAGS: 00000246 ORIGRAX: 0000000000000014 RAX: ffffffffffffffda RBX: 00007f6364a15fa0 RCX: 00007f636479c629 RDX: 0000000000000001 RSI: 0000200000000080 RDI: 0000000000000003 RBP: 00007f6364832b39 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f6364a15fac R14: 00007f6364a15fa0 R15: 00007f6364a15fa0 </TASK>

[1]: https://lore.kernel.org/all/20260226201600.222044-1-alice.kernel@fastmail.im/

Affected Software

257 affected componentsFixes available
Linux Linux kernel (l2tp)
Linux Linux kernel>=2.6.23<5.10.258
Linux Linux kernel>=5.11<5.15.209
Linux Linux kernel>=5.16<6.1.175
Linux Linux kernel>=6.2<6.6.136
Linux Linux kernel>=6.7<6.12.83
Linux Linux kernel>=6.13<6.18.24
Linux Linux kernel>=6.19<6.19.14
Linux Linux kernel=7.0-rc1
Linux Linux kernel=7.0-rc2
Linux Linux kernel=7.0-rc3
Linux Linux kernel=7.0-rc4
Linux Linux kernel=7.0-rc5
Linux Linux kernel=7.0-rc6
Linux Linux kernel=7.0-rc7
ubuntu/linux*
ubuntu/linux-aws*
ubuntu/linux-azure*
ubuntu/linux-lts-xenial*
ubuntu/linux*
ubuntu/linux-aws*
ubuntu/linux-aws-hwe*
ubuntu/linux-azure*
ubuntu/linux-gcp*
ubuntu/linux-hwe*
ubuntu/linux-hwe-edge*
ubuntu/linux-kvm*
ubuntu/linux-oracle*
ubuntu/linux-fips*
ubuntu/linux-fips*
ubuntu/linux*
ubuntu/linux-aws*
ubuntu/linux-aws-5.0*
ubuntu/linux-aws-5.3*
ubuntu/linux-aws-5.4*
ubuntu/linux-azure*
ubuntu/linux-azure-4.15*
ubuntu/linux-azure-5.3*
ubuntu/linux-azure-5.4*
ubuntu/linux-azure-edge*
ubuntu/linux-gcp*
ubuntu/linux-gcp-4.15*
ubuntu/linux-gcp-5.3*
ubuntu/linux-gcp-5.4*
ubuntu/linux-gke-4.15*
ubuntu/linux-gke-5.4*
ubuntu/linux-gkeop-5.4*
ubuntu/linux-hwe*
ubuntu/linux-hwe-5.4*
ubuntu/linux-hwe-edge*
ubuntu/linux-ibm-5.4*
ubuntu/linux-kvm*
ubuntu/linux-oem*
ubuntu/linux-oracle*
ubuntu/linux-oracle-5.0*
ubuntu/linux-oracle-5.3*
ubuntu/linux-oracle-5.4*
ubuntu/linux-raspi-5.4*
ubuntu/linux-aws-fips*
ubuntu/linux-azure-fips*
ubuntu/linux-fips*
ubuntu/linux-gcp-fips*
ubuntu/linux-aws-fips*
ubuntu/linux-azure-fips*
ubuntu/linux-fips*
ubuntu/linux-gcp-fips*
ubuntu/linux*
ubuntu/linux-aws*
ubuntu/linux-aws-5.11*
ubuntu/linux-aws-5.13*
ubuntu/linux-aws-5.15<5.15.0-1112.119~20.04.1
5.15.0-1112.119~20.04.1
ubuntu/linux-aws-5.8*
ubuntu/linux-azure*
ubuntu/linux-azure-5.11*
ubuntu/linux-azure-5.13*
ubuntu/linux-azure-5.15<5.15.0-1117.126~20.04.1
5.15.0-1117.126~20.04.1
ubuntu/linux-azure-5.8*
ubuntu/linux-azure-fde*
ubuntu/linux-azure-fde-5.15<5.15.0-1117.126~20.04.2
5.15.0-1117.126~20.04.2
ubuntu/linux-bluefield*
ubuntu/linux-gcp*
ubuntu/linux-gcp-5.11*
ubuntu/linux-gcp-5.13*
ubuntu/linux-gcp-5.15<5.15.0-1112.122~20.04.1
5.15.0-1112.122~20.04.1
ubuntu/linux-gcp-5.8*
ubuntu/linux-gke*
ubuntu/linux-gke-5.15*
ubuntu/linux-gkeop*
ubuntu/linux-gkeop-5.15*
ubuntu/linux-hwe-5.11*
ubuntu/linux-hwe-5.13*
ubuntu/linux-hwe-5.15<5.15.0-186.196~20.04.1
5.15.0-186.196~20.04.1
ubuntu/linux-hwe-5.8*
ubuntu/linux-ibm*
ubuntu/linux-ibm-5.15<5.15.0-1106.110~20.04.1
5.15.0-1106.110~20.04.1
ubuntu/linux-intel-5.13*
ubuntu/linux-intel-iotg-5.15<5.15.0-1107.113~20.04.1
5.15.0-1107.113~20.04.1
ubuntu/linux-iot*
ubuntu/linux-kvm*
ubuntu/linux-lowlatency-hwe-5.15<5.15.0-184.194~20.04.1
5.15.0-184.194~20.04.1
ubuntu/linux-nvidia-tegra-5.15<5.15.0-1064.66~20.04.1
5.15.0-1064.66~20.04.1
ubuntu/linux-oem-5.10*
ubuntu/linux-oem-5.13*
ubuntu/linux-oem-5.6*
ubuntu/linux-oracle*
ubuntu/linux-oracle-5.11*
ubuntu/linux-oracle-5.13*
ubuntu/linux-oracle-5.15<5.15.0-1109.115~20.04.1
5.15.0-1109.115~20.04.1
ubuntu/linux-oracle-5.8*
ubuntu/linux-raspi*
ubuntu/linux-raspi2*
ubuntu/linux-riscv*
ubuntu/linux-riscv-5.11*
ubuntu/linux-riscv-5.15<5.15.0-1106.110~20.04.1
5.15.0-1106.110~20.04.1
ubuntu/linux-riscv-5.8*
ubuntu/linux-xilinx-zynqmp*
ubuntu/linux-aws-fips*
ubuntu/linux-azure-fips*
ubuntu/linux-fips*
ubuntu/linux-gcp-fips*
ubuntu/linux-aws-fips*
ubuntu/linux-azure-fips*
ubuntu/linux-fips*
ubuntu/linux-gcp-fips*
ubuntu/linux<5.15.0-186.196
5.15.0-186.196
ubuntu/linux-allwinner-5.19*
ubuntu/linux-aws<5.15.0-1112.119
5.15.0-1112.119
ubuntu/linux-aws-5.19*
ubuntu/linux-aws-6.2*
ubuntu/linux-aws-6.5*
ubuntu/linux-aws-6.8<6.8.0-1061.64~22.04.1
6.8.0-1061.64~22.04.1
ubuntu/linux-azure<5.15.0-1117.126
5.15.0-1117.126
ubuntu/linux-azure-5.19*
ubuntu/linux-azure-6.2*
ubuntu/linux-azure-6.5*
ubuntu/linux-azure-6.8<6.8.0-1063.71~22.04.1
6.8.0-1063.71~22.04.1
ubuntu/linux-azure-fde<5.15.0-1117.126
5.15.0-1117.126
ubuntu/linux-azure-fde-5.19*
ubuntu/linux-azure-fde-6.2*
ubuntu/linux-azure-fde-6.8<6.8.0-1062.69~22.04.1
6.8.0-1062.69~22.04.1
ubuntu/linux-gcp<5.15.0-1112.122
5.15.0-1112.122
ubuntu/linux-gcp-5.19*
ubuntu/linux-gcp-6.2*
ubuntu/linux-gcp-6.5*
ubuntu/linux-gcp-6.8<6.8.0-1064.72~22.04.1
6.8.0-1064.72~22.04.1
ubuntu/linux-gke<5.15.0-1108.114
5.15.0-1108.114
ubuntu/linux-gkeop<5.15.0-1095.103
5.15.0-1095.103
ubuntu/linux-hwe-5.19*
ubuntu/linux-hwe-6.2*
ubuntu/linux-hwe-6.5*
ubuntu/linux-hwe-6.8<6.8.0-136.136~22.04.1
6.8.0-136.136~22.04.1
ubuntu/linux-ibm<5.15.0-1106.110
5.15.0-1106.110
ubuntu/linux-ibm-6.8<6.8.0-1061.62~22.04.1
6.8.0-1061.62~22.04.1
ubuntu/linux-intel-iot-realtime*
ubuntu/linux-intel-iotg<5.15.0-1107.113
5.15.0-1107.113
ubuntu/linux-kvm<5.15.0-1104.109
5.15.0-1104.109
ubuntu/linux-lowlatency<5.15.0-184.194
5.15.0-184.194
ubuntu/linux-lowlatency-hwe-5.19*
ubuntu/linux-lowlatency-hwe-6.2*
ubuntu/linux-lowlatency-hwe-6.5*
ubuntu/linux-lowlatency-hwe-6.8<6.8.0-136.136.2~22.04.1
6.8.0-136.136.2~22.04.1
ubuntu/linux-nvidia<5.15.0-1107.108
5.15.0-1107.108
ubuntu/linux-nvidia-6.2*
ubuntu/linux-nvidia-6.5*
ubuntu/linux-nvidia-6.8<6.8.0-1059.62~22.04.1
6.8.0-1059.62~22.04.1
ubuntu/linux-nvidia-tegra<5.15.0-1064.66
5.15.0-1064.66
ubuntu/linux-nvidia-tegra-igx<5.15.0-1053.53
5.15.0-1053.53
ubuntu/linux-oem-5.17*
ubuntu/linux-oem-6.0*
ubuntu/linux-oem-6.1*
ubuntu/linux-oem-6.5*
ubuntu/linux-oracle<5.15.0-1109.115
5.15.0-1109.115
ubuntu/linux-oracle-6.5*
ubuntu/linux-oracle-6.8<6.8.0-1058.61~22.04.1
6.8.0-1058.61~22.04.1
ubuntu/linux-raspi<5.15.0-1106.109
5.15.0-1106.109
ubuntu/linux-realtime*
ubuntu/linux-riscv*
ubuntu/linux-riscv-5.19*
ubuntu/linux-riscv-6.5*
ubuntu/linux-riscv-6.8<6.8.0-136.136~22.04.3
6.8.0-136.136~22.04.3
ubuntu/linux-starfive-5.19*
ubuntu/linux-starfive-6.2*
ubuntu/linux-starfive-6.5*
ubuntu/linux-xilinx-zynqmp<5.15.0-1075.79
5.15.0-1075.79
ubuntu/linux-bluefield<5.15.0-1096.98
5.15.0-1096.98
ubuntu/linux-intel-iot-realtime<5.15.0-1104.106
5.15.0-1104.106
ubuntu/linux-realtime<5.15.0-1111.120
5.15.0-1111.120
ubuntu/linux-realtime-6.8<6.8.1-1056.57~22.04.2
6.8.1-1056.57~22.04.2
ubuntu/linux-aws-fips*
ubuntu/linux-azure-fips*
ubuntu/linux-fips*
ubuntu/linux-gcp-fips*
ubuntu/linux-aws-fips<5.15.0-1112.119+fips1
5.15.0-1112.119+fips1
ubuntu/linux-azure-fips<5.15.0-1117.126+fips1
5.15.0-1117.126+fips1
ubuntu/linux-fips<5.15.0-186.196+fips1
5.15.0-186.196+fips1
ubuntu/linux-gcp-fips<5.15.0-1112.122+fips1
5.15.0-1112.122+fips1
ubuntu/linux<6.8.0-136.136
6.8.0-136.136
ubuntu/linux-aws<6.8.0-1061.64
6.8.0-1061.64
ubuntu/linux-aws-6.14*
ubuntu/linux-aws-6.17*
ubuntu/linux-azure<6.8.0-1063.71
6.8.0-1063.71
ubuntu/linux-azure-6.11*
ubuntu/linux-azure-6.14*
ubuntu/linux-azure-6.17*
ubuntu/linux-azure-fde<6.8.0-1062.69
6.8.0-1062.69
ubuntu/linux-azure-fde-6.14*
ubuntu/linux-azure-nvidia*
ubuntu/linux-azure-nvidia-6.14*
ubuntu/linux-gcp<6.8.0-1064.72
6.8.0-1064.72
ubuntu/linux-gcp-6.11*
ubuntu/linux-gcp-6.14*
ubuntu/linux-gke<6.8.0-1059.67
6.8.0-1059.67
ubuntu/linux-gkeop<6.8.0-1046.50
6.8.0-1046.50
ubuntu/linux-hwe-6.11*
ubuntu/linux-hwe-6.14*
ubuntu/linux-hwe-6.17*
ubuntu/linux-ibm<6.8.0-1061.62
6.8.0-1061.62
ubuntu/linux-lowlatency<6.8.0-136.136.2
6.8.0-136.136.2
ubuntu/linux-lowlatency-hwe-6.11*
ubuntu/linux-nvidia<6.8.0-1059.62
6.8.0-1059.62
ubuntu/linux-nvidia-6.11*
ubuntu/linux-nvidia-6.17*
ubuntu/linux-nvidia-lowlatency<6.8.0-1059.62.1
6.8.0-1059.62.1
ubuntu/linux-nvidia-tegra<6.8.0-1030.31
6.8.0-1030.31
ubuntu/linux-oem-6.11*
ubuntu/linux-oem-6.14*
ubuntu/linux-oem-6.17*
ubuntu/linux-oem-6.8*
ubuntu/linux-oracle<6.8.0-1058.61
6.8.0-1058.61
ubuntu/linux-oracle-6.14*
ubuntu/linux-oracle-6.17*
ubuntu/linux-raspi<6.8.0-1061.65
6.8.0-1061.65
ubuntu/linux-raspi-realtime*
ubuntu/linux-realtime*
ubuntu/linux-riscv*
ubuntu/linux-riscv-6.14*
ubuntu/linux-riscv-6.17*
ubuntu/linux-xilinx<6.8.0-1033.34
6.8.0-1033.34
ubuntu/linux-bluefield<6.8.0-1028.33
6.8.0-1028.33
ubuntu/linux-raspi-realtime<6.8.0-2050.52
6.8.0-2050.52
ubuntu/linux-realtime<6.8.1-1056.57
6.8.1-1056.57
ubuntu/linux-realtime-6.14*
ubuntu/linux-realtime-6.17*
ubuntu/linux-aws-fips<6.8.0-1061.64+fips1
6.8.0-1061.64+fips1
ubuntu/linux-azure-fips<6.8.0-1063.71+fips2
6.8.0-1063.71+fips2
ubuntu/linux-fips<6.8.0-136.136+fips2
6.8.0-136.136+fips2
ubuntu/linux-gcp-fips<6.8.0-1064.72+fips1
6.8.0-1064.72+fips1
ubuntu/linux*
ubuntu/linux-aws*
ubuntu/linux-azure*
ubuntu/linux-azure-fde*
ubuntu/linux-gcp*
ubuntu/linux-oracle*
ubuntu/linux-raspi*
ubuntu/linux-realtime*
ubuntu/linux-riscv*
ubuntu/linux-nvidia<7.0.0-1006.6
7.0.0-1006.6

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade ubuntu/linux-aws-5.15 to a version that resolves this vulnerability.

    Fixed in 5.15.0-1112.119~20.04.1
  2. Upgrade

    Upgrade ubuntu/linux-azure-5.15 to a version that resolves this vulnerability.

    Fixed in 5.15.0-1117.126~20.04.1
  3. Upgrade

    Upgrade ubuntu/linux-azure-fde-5.15 to a version that resolves this vulnerability.

    Fixed in 5.15.0-1117.126~20.04.2
  4. Upgrade

    Upgrade ubuntu/linux-gcp-5.15 to a version that resolves this vulnerability.

    Fixed in 5.15.0-1112.122~20.04.1
  5. Upgrade

    Upgrade ubuntu/linux-hwe-5.15 to a version that resolves this vulnerability.

    Fixed in 5.15.0-186.196~20.04.1
  6. Upgrade

    Upgrade ubuntu/linux-ibm-5.15 to a version that resolves this vulnerability.

    Fixed in 5.15.0-1106.110~20.04.1
  7. Upgrade

    Upgrade ubuntu/linux-intel-iotg-5.15 to a version that resolves this vulnerability.

    Fixed in 5.15.0-1107.113~20.04.1
  8. Upgrade

    Upgrade ubuntu/linux-lowlatency-hwe-5.15 to a version that resolves this vulnerability.

    Fixed in 5.15.0-184.194~20.04.1
  9. Upgrade

    Upgrade ubuntu/linux-nvidia-tegra-5.15 to a version that resolves this vulnerability.

    Fixed in 5.15.0-1064.66~20.04.1
  10. Upgrade

    Upgrade ubuntu/linux-oracle-5.15 to a version that resolves this vulnerability.

    Fixed in 5.15.0-1109.115~20.04.1
  11. Upgrade

    Upgrade ubuntu/linux-riscv-5.15 to a version that resolves this vulnerability.

    Fixed in 5.15.0-1106.110~20.04.1
  12. Upgrade

    Upgrade ubuntu/linux to a version that resolves this vulnerability.

    Fixed in 5.15.0-186.196
  13. Upgrade

    Upgrade ubuntu/linux-aws to a version that resolves this vulnerability.

    Fixed in 5.15.0-1112.119
  14. Upgrade

    Upgrade ubuntu/linux-aws-6.8 to a version that resolves this vulnerability.

    Fixed in 6.8.0-1061.64~22.04.1
  15. Upgrade

    Upgrade ubuntu/linux-azure to a version that resolves this vulnerability.

    Fixed in 5.15.0-1117.126
  16. Upgrade

    Upgrade ubuntu/linux-azure-6.8 to a version that resolves this vulnerability.

    Fixed in 6.8.0-1063.71~22.04.1
  17. Upgrade

    Upgrade ubuntu/linux-azure-fde to a version that resolves this vulnerability.

    Fixed in 5.15.0-1117.126
  18. Upgrade

    Upgrade ubuntu/linux-azure-fde-6.8 to a version that resolves this vulnerability.

    Fixed in 6.8.0-1062.69~22.04.1
  19. Upgrade

    Upgrade ubuntu/linux-gcp to a version that resolves this vulnerability.

    Fixed in 5.15.0-1112.122
  20. Upgrade

    Upgrade ubuntu/linux-gcp-6.8 to a version that resolves this vulnerability.

    Fixed in 6.8.0-1064.72~22.04.1
  21. Upgrade

    Upgrade ubuntu/linux-gke to a version that resolves this vulnerability.

    Fixed in 5.15.0-1108.114
  22. Upgrade

    Upgrade ubuntu/linux-gkeop to a version that resolves this vulnerability.

    Fixed in 5.15.0-1095.103
  23. Upgrade

    Upgrade ubuntu/linux-hwe-6.8 to a version that resolves this vulnerability.

    Fixed in 6.8.0-136.136~22.04.1
  24. Upgrade

    Upgrade ubuntu/linux-ibm to a version that resolves this vulnerability.

    Fixed in 5.15.0-1106.110
  25. Upgrade

    Upgrade ubuntu/linux-ibm-6.8 to a version that resolves this vulnerability.

    Fixed in 6.8.0-1061.62~22.04.1
  26. Upgrade

    Upgrade ubuntu/linux-intel-iotg to a version that resolves this vulnerability.

    Fixed in 5.15.0-1107.113
  27. Upgrade

    Upgrade ubuntu/linux-kvm to a version that resolves this vulnerability.

    Fixed in 5.15.0-1104.109
  28. Upgrade

    Upgrade ubuntu/linux-lowlatency to a version that resolves this vulnerability.

    Fixed in 5.15.0-184.194
  29. Upgrade

    Upgrade ubuntu/linux-lowlatency-hwe-6.8 to a version that resolves this vulnerability.

    Fixed in 6.8.0-136.136.2~22.04.1
  30. Upgrade

    Upgrade ubuntu/linux-nvidia to a version that resolves this vulnerability.

    Fixed in 5.15.0-1107.108
  31. Upgrade

    Upgrade ubuntu/linux-nvidia-6.8 to a version that resolves this vulnerability.

    Fixed in 6.8.0-1059.62~22.04.1
  32. Upgrade

    Upgrade ubuntu/linux-nvidia-tegra to a version that resolves this vulnerability.

    Fixed in 5.15.0-1064.66
  33. Upgrade

    Upgrade ubuntu/linux-nvidia-tegra-igx to a version that resolves this vulnerability.

    Fixed in 5.15.0-1053.53
  34. Upgrade

    Upgrade ubuntu/linux-oracle to a version that resolves this vulnerability.

    Fixed in 5.15.0-1109.115
  35. Upgrade

    Upgrade ubuntu/linux-oracle-6.8 to a version that resolves this vulnerability.

    Fixed in 6.8.0-1058.61~22.04.1
  36. Upgrade

    Upgrade ubuntu/linux-raspi to a version that resolves this vulnerability.

    Fixed in 5.15.0-1106.109
  37. Upgrade

    Upgrade ubuntu/linux-riscv-6.8 to a version that resolves this vulnerability.

    Fixed in 6.8.0-136.136~22.04.3
  38. Upgrade

    Upgrade ubuntu/linux-xilinx-zynqmp to a version that resolves this vulnerability.

    Fixed in 5.15.0-1075.79
  39. Upgrade

    Upgrade ubuntu/linux-bluefield to a version that resolves this vulnerability.

    Fixed in 5.15.0-1096.98
  40. Upgrade

    Upgrade ubuntu/linux-intel-iot-realtime to a version that resolves this vulnerability.

    Fixed in 5.15.0-1104.106
  41. Upgrade

    Upgrade ubuntu/linux-realtime to a version that resolves this vulnerability.

    Fixed in 5.15.0-1111.120
  42. Upgrade

    Upgrade ubuntu/linux-realtime-6.8 to a version that resolves this vulnerability.

    Fixed in 6.8.1-1056.57~22.04.2
  43. Upgrade

    Upgrade ubuntu/linux-aws-fips to a version that resolves this vulnerability.

    Fixed in 5.15.0-1112.119+fips1
  44. Upgrade

    Upgrade ubuntu/linux-azure-fips to a version that resolves this vulnerability.

    Fixed in 5.15.0-1117.126+fips1
  45. Upgrade

    Upgrade ubuntu/linux-fips to a version that resolves this vulnerability.

    Fixed in 5.15.0-186.196+fips1
  46. Upgrade

    Upgrade ubuntu/linux-gcp-fips to a version that resolves this vulnerability.

    Fixed in 5.15.0-1112.122+fips1
  47. Upgrade

    Upgrade ubuntu/linux to a version that resolves this vulnerability.

    Fixed in 6.8.0-136.136
  48. Upgrade

    Upgrade ubuntu/linux-aws to a version that resolves this vulnerability.

    Fixed in 6.8.0-1061.64
  49. Upgrade

    Upgrade ubuntu/linux-azure to a version that resolves this vulnerability.

    Fixed in 6.8.0-1063.71
  50. Upgrade

    Upgrade ubuntu/linux-azure-fde to a version that resolves this vulnerability.

    Fixed in 6.8.0-1062.69
  51. Upgrade

    Upgrade ubuntu/linux-gcp to a version that resolves this vulnerability.

    Fixed in 6.8.0-1064.72
  52. Upgrade

    Upgrade ubuntu/linux-gke to a version that resolves this vulnerability.

    Fixed in 6.8.0-1059.67
  53. Upgrade

    Upgrade ubuntu/linux-gkeop to a version that resolves this vulnerability.

    Fixed in 6.8.0-1046.50
  54. Upgrade

    Upgrade ubuntu/linux-ibm to a version that resolves this vulnerability.

    Fixed in 6.8.0-1061.62
  55. Upgrade

    Upgrade ubuntu/linux-lowlatency to a version that resolves this vulnerability.

    Fixed in 6.8.0-136.136.2
  56. Upgrade

    Upgrade ubuntu/linux-nvidia to a version that resolves this vulnerability.

    Fixed in 6.8.0-1059.62
  57. Upgrade

    Upgrade ubuntu/linux-nvidia-lowlatency to a version that resolves this vulnerability.

    Fixed in 6.8.0-1059.62.1
  58. Upgrade

    Upgrade ubuntu/linux-nvidia-tegra to a version that resolves this vulnerability.

    Fixed in 6.8.0-1030.31
  59. Upgrade

    Upgrade ubuntu/linux-oracle to a version that resolves this vulnerability.

    Fixed in 6.8.0-1058.61
  60. Upgrade

    Upgrade ubuntu/linux-raspi to a version that resolves this vulnerability.

    Fixed in 6.8.0-1061.65
  61. Upgrade

    Upgrade ubuntu/linux-xilinx to a version that resolves this vulnerability.

    Fixed in 6.8.0-1033.34
  62. Upgrade

    Upgrade ubuntu/linux-bluefield to a version that resolves this vulnerability.

    Fixed in 6.8.0-1028.33
  63. Upgrade

    Upgrade ubuntu/linux-raspi-realtime to a version that resolves this vulnerability.

    Fixed in 6.8.0-2050.52
  64. Upgrade

    Upgrade ubuntu/linux-realtime to a version that resolves this vulnerability.

    Fixed in 6.8.1-1056.57
  65. Upgrade

    Upgrade ubuntu/linux-aws-fips to a version that resolves this vulnerability.

    Fixed in 6.8.0-1061.64+fips1
  66. Upgrade

    Upgrade ubuntu/linux-azure-fips to a version that resolves this vulnerability.

    Fixed in 6.8.0-1063.71+fips2
  67. Upgrade

    Upgrade ubuntu/linux-fips to a version that resolves this vulnerability.

    Fixed in 6.8.0-136.136+fips2
  68. Upgrade

    Upgrade ubuntu/linux-gcp-fips to a version that resolves this vulnerability.

    Fixed in 6.8.0-1064.72+fips1
  69. Upgrade

    Upgrade ubuntu/linux-nvidia to a version that resolves this vulnerability.

    Fixed in 7.0.0-1006.6
  70. Compensating control

    In Linux kernel L2TP UDP encapsulation, add an overflow check that drops packets with len >= 65536u before assigning the 16-bit UDP length field, preventing packets with a trimmed UDP length from being sent to the wire.

Event History

May 6, 2026
CVE Published
via MITRE·07:40 AM
Data Sourced
via MITRE·07:40 AM
Description
Data Sourced
via OSV·10:16 AM
DescriptionSeverityAffected Software
Data Sourced
via NVD·10:16 AM
RemedyDescriptionSeverityWeaknessAffected Software

Frequently Asked Questions

1

What access and capabilities are needed to trigger this issue?

The CVSS vector indicates local access with low privileges is required. The reproducer creates a PPPoL2TP socket using UDP encapsulation and writes an oversized packet larger than the 16-bit UDP length limit.

2

What is the effect of sending an oversized packet on an unpatched system?

The UDP length field can overflow and be truncated to 16 bits. This can result in a packet being sent with a trimmed UDP length value and can cause an availability impact.

3

Is a fix available?

Yes. The fix adds an overflow check that drops packets whose length cannot be represented in the UDP length field, preventing transmission with a truncated length.

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