CVE-2025-39946: tls: make sure to abort the stream if headers are bogus

Published Oct 4, 2025
·
Updated

In multiple locations, there is a possible out of bounds write due to a missing bounds check. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.

Other sources

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

tls: make sure to abort the stream if headers are bogus

Normally we wait for the socket to buffer up the whole record before we service it. If the socket has a tiny buffer, however, we read out the data sooner, to prevent connection stalls. Make sure that we abort the connection when we find out late that the record is actually invalid. Retrying the parsing is fine in itself but since we copy some more data each time before we parse we can overflow the allocated skb space.

Constructing a scenario in which we're under pressure without enough data in the socket to parse the length upfront is quite hard. syzbot figured out a way to do this by serving us the header in small OOB sends, and then filling in the recvbuf with a large normal send.

Make sure that tlsrxmsgsize() aborts strp, if we reach an invalid record there's really no way to recover.

— MITRE

In tlsrxmsgsize of tlssw.c, there is a possible out of bounds write due to an incorrect bounds check. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.

— OSV

Affected Software

148 affected componentsFixes available
Linux Kernel
Microsoft azl3 kernel 6.6.96.2-2
Microsoft azl3 kernel 6.6.104.2-4
Patch available
Linux Linux kernel>=6.0<6.1.154
Linux Linux kernel>=6.2<6.6.108
Linux Linux kernel>=6.7<6.12.49
Linux Linux kernel>=6.13<6.16.9
Linux Linux kernel=6.17-rc1
Linux Linux kernel=6.17-rc2
Linux Linux kernel=6.17-rc3
Linux Linux kernel=6.17-rc4
Linux Linux kernel=6.17-rc5
Linux Linux kernel=6.17-rc6
Google Android
ubuntu/linux-hwe-edge*
ubuntu/linux-aws-5.0*
ubuntu/linux-aws-5.3*
ubuntu/linux-azure*
ubuntu/linux-azure-5.3*
ubuntu/linux-azure-edge*
ubuntu/linux-gcp*
ubuntu/linux-gcp-5.3*
ubuntu/linux-gke-4.15*
ubuntu/linux-gke-5.4*
ubuntu/linux-gkeop-5.4*
ubuntu/linux-hwe*
ubuntu/linux-hwe-edge*
ubuntu/linux-oem*
ubuntu/linux-oracle-5.0*
ubuntu/linux-oracle-5.3*
ubuntu/linux-aws-5.11*
ubuntu/linux-aws-5.13*
ubuntu/linux-aws-5.8*
ubuntu/linux-azure-5.11*
ubuntu/linux-azure-5.13*
ubuntu/linux-azure-5.8*
ubuntu/linux-azure-fde*
ubuntu/linux-gcp-5.11*
ubuntu/linux-gcp-5.13*
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-5.8*
ubuntu/linux-intel-5.13*
ubuntu/linux-oem-5.10*
ubuntu/linux-oem-5.13*
ubuntu/linux-oem-5.6*
ubuntu/linux-oracle-5.11*
ubuntu/linux-oracle-5.13*
ubuntu/linux-oracle-5.8*
ubuntu/linux-raspi2*
ubuntu/linux-riscv*
ubuntu/linux-riscv-5.11*
ubuntu/linux-riscv-5.8*
ubuntu/linux-allwinner-5.19*
ubuntu/linux-aws-5.19*
ubuntu/linux-aws-6.2*
ubuntu/linux-aws-6.5*
ubuntu/linux-aws-6.8<6.8.0-1046.49~22.04.1
6.8.0-1046.49~22.04.1
ubuntu/linux-azure-5.19*
ubuntu/linux-azure-6.2*
ubuntu/linux-azure-6.5*
ubuntu/linux-azure-6.8<6.8.0-1051.57~22.04.1
6.8.0-1051.57~22.04.1
ubuntu/linux-azure-fde-5.19*
ubuntu/linux-azure-fde-6.2*
ubuntu/linux-azure-fde-6.8<6.8.0-1046.53~22.04.1
6.8.0-1046.53~22.04.1
ubuntu/linux-gcp-5.19*
ubuntu/linux-gcp-6.2*
ubuntu/linux-gcp-6.5*
ubuntu/linux-gcp-6.8<6.8.0-1047.50~22.04.2
6.8.0-1047.50~22.04.2
ubuntu/linux-hwe-5.19*
ubuntu/linux-hwe-6.2*
ubuntu/linux-hwe-6.5*
ubuntu/linux-hwe-6.8<6.8.0-100.100~22.04.1
6.8.0-100.100~22.04.1
ubuntu/linux-ibm-6.8<6.8.0-1044.44~22.04.1
6.8.0-1044.44~22.04.1
ubuntu/linux-intel-iot-realtime*
ubuntu/linux-lowlatency-hwe-5.19*
ubuntu/linux-lowlatency-hwe-6.2*
ubuntu/linux-lowlatency-hwe-6.5*
ubuntu/linux-lowlatency-hwe-6.8<6.8.0-100.100.1~22.04.1
6.8.0-100.100.1~22.04.1
ubuntu/linux-nvidia-6.2*
ubuntu/linux-nvidia-6.5*
ubuntu/linux-nvidia-6.8<6.8.0-1046.49~22.04.1
6.8.0-1046.49~22.04.1
ubuntu/linux-oem-5.17*
ubuntu/linux-oem-6.0*
ubuntu/linux-oem-6.1*
ubuntu/linux-oem-6.5*
ubuntu/linux-oracle-6.5*
ubuntu/linux-oracle-6.8<6.8.0-1043.44~22.04.1
6.8.0-1043.44~22.04.1
ubuntu/linux-realtime*
ubuntu/linux-riscv*
ubuntu/linux-riscv-5.19*
ubuntu/linux-riscv-6.5*
ubuntu/linux-riscv-6.8<6.8.0-100.100~22.04.1
6.8.0-100.100~22.04.1
ubuntu/linux-starfive-5.19*
ubuntu/linux-starfive-6.2*
ubuntu/linux-starfive-6.5*
ubuntu/linux-realtime-6.8<6.8.1-1041.42~22.04.1
6.8.1-1041.42~22.04.1
ubuntu/linux<6.8.0-100.100
6.8.0-100.100
ubuntu/linux-aws<6.8.0-1046.49
6.8.0-1046.49
ubuntu/linux-aws-6.14<6.14.0-1018.18~24.04.1
6.14.0-1018.18~24.04.1
ubuntu/linux-azure<6.8.0-1046.52
6.8.0-1046.52
ubuntu/linux-azure-6.11*
ubuntu/linux-azure-6.14<6.14.0-1017.17~24.04.1
6.14.0-1017.17~24.04.1
ubuntu/linux-azure-fde<6.8.0-1046.53
6.8.0-1046.53
ubuntu/linux-azure-fde-6.14*
ubuntu/linux-azure-nvidia*
ubuntu/linux-azure-nvidia-6.14*
ubuntu/linux-gcp<6.8.0-1047.50
6.8.0-1047.50
ubuntu/linux-gcp-6.11*
ubuntu/linux-gcp-6.14*
ubuntu/linux-gke<6.8.0-1043.48
6.8.0-1043.48
ubuntu/linux-gkeop<6.8.0-1030.33
6.8.0-1030.33
ubuntu/linux-hwe-6.11*
ubuntu/linux-ibm<6.8.0-1044.44
6.8.0-1044.44
ubuntu/linux-intel*
ubuntu/linux-lowlatency<6.8.0-100.100.1
6.8.0-100.100.1
ubuntu/linux-lowlatency-hwe-6.11*
ubuntu/linux-nvidia<6.8.0-1046.49
6.8.0-1046.49
ubuntu/linux-nvidia-6.11*
ubuntu/linux-nvidia-lowlatency<6.8.0-1046.49.1
6.8.0-1046.49.1
ubuntu/linux-nvidia-tegra<6.8.0-1020.20
6.8.0-1020.20
ubuntu/linux-oem-6.11*
ubuntu/linux-oem-6.14<6.14.0-1017.17
6.14.0-1017.17
ubuntu/linux-oem-6.8*
ubuntu/linux-oracle<6.8.0-1043.44
6.8.0-1043.44
ubuntu/linux-oracle-6.14*
ubuntu/linux-raspi<6.8.0-1047.51
6.8.0-1047.51
ubuntu/linux-raspi-realtime*
ubuntu/linux-realtime*
ubuntu/linux-riscv*
ubuntu/linux-riscv-6.14<6.14.0-37.37.1~24.04.1
6.14.0-37.37.1~24.04.1
ubuntu/linux-xilinx<6.8.0-1023.24
6.8.0-1023.24
ubuntu/linux-bluefield<6.8.0-1016.20
6.8.0-1016.20
ubuntu/linux-raspi-realtime<6.8.0-2037.38
6.8.0-2037.38
ubuntu/linux-realtime<6.8.1-1041.42
6.8.1-1041.42
ubuntu/linux-realtime-6.14<6.14.0-1017.17~24.04.1
6.14.0-1017.17~24.04.1
ubuntu/linux-aws-fips<6.8.0-1046.49+fips1
6.8.0-1046.49+fips1
ubuntu/linux-azure-fips<6.8.0-1046.52+fips1
6.8.0-1046.52+fips1
ubuntu/linux-fips<6.8.0-100.100+fips1
6.8.0-100.100+fips1
ubuntu/linux-gcp-fips<6.8.0-1047.50+fips1
6.8.0-1047.50+fips1
ubuntu/linux-azure-fde*
android/:linux_kernel:>=:0<:2026-03-05
:2026-03-05
debian/linux
6.1.176-16.1.190-16.12.107-16.12.115-27.2.15-17.3.3-1

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

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

    Fixed in 6.8.0-1046.49~22.04.1
  2. Upgrade

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

    Fixed in 6.8.0-1051.57~22.04.1
  3. Upgrade

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

    Fixed in 6.8.0-1046.53~22.04.1
  4. Upgrade

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

    Fixed in 6.8.0-1047.50~22.04.2
  5. Upgrade

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

    Fixed in 6.8.0-100.100~22.04.1
  6. Upgrade

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

    Fixed in 6.8.0-1044.44~22.04.1
  7. Upgrade

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

    Fixed in 6.8.0-100.100.1~22.04.1
  8. Upgrade

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

    Fixed in 6.8.0-1046.49~22.04.1
  9. Upgrade

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

    Fixed in 6.8.0-1043.44~22.04.1
  10. Upgrade

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

    Fixed in 6.8.0-100.100~22.04.1
  11. Upgrade

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

    Fixed in 6.8.1-1041.42~22.04.1
  12. Upgrade

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

    Fixed in 6.8.0-100.100
  13. Upgrade

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

    Fixed in 6.8.0-1046.49
  14. Upgrade

    Upgrade ubuntu/linux-aws-6.14 to a version that resolves this vulnerability.

    Fixed in 6.14.0-1018.18~24.04.1
  15. Upgrade

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

    Fixed in 6.8.0-1046.52
  16. Upgrade

    Upgrade ubuntu/linux-azure-6.14 to a version that resolves this vulnerability.

    Fixed in 6.14.0-1017.17~24.04.1
  17. Upgrade

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

    Fixed in 6.8.0-1046.53
  18. Upgrade

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

    Fixed in 6.8.0-1047.50
  19. Upgrade

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

    Fixed in 6.8.0-1043.48
  20. Upgrade

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

    Fixed in 6.8.0-1030.33
  21. Upgrade

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

    Fixed in 6.8.0-1044.44
  22. Upgrade

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

    Fixed in 6.8.0-100.100.1
  23. Upgrade

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

    Fixed in 6.8.0-1046.49
  24. Upgrade

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

    Fixed in 6.8.0-1046.49.1
  25. Upgrade

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

    Fixed in 6.8.0-1020.20
  26. Upgrade

    Upgrade ubuntu/linux-oem-6.14 to a version that resolves this vulnerability.

    Fixed in 6.14.0-1017.17
  27. Upgrade

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

    Fixed in 6.8.0-1043.44
  28. Upgrade

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

    Fixed in 6.8.0-1047.51
  29. Upgrade

    Upgrade ubuntu/linux-riscv-6.14 to a version that resolves this vulnerability.

    Fixed in 6.14.0-37.37.1~24.04.1
  30. Upgrade

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

    Fixed in 6.8.0-1023.24
  31. Upgrade

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

    Fixed in 6.8.0-1016.20
  32. Upgrade

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

    Fixed in 6.8.0-2037.38
  33. Upgrade

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

    Fixed in 6.8.1-1041.42
  34. Upgrade

    Upgrade ubuntu/linux-realtime-6.14 to a version that resolves this vulnerability.

    Fixed in 6.14.0-1017.17~24.04.1
  35. Upgrade

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

    Fixed in 6.8.0-1046.49+fips1
  36. Upgrade

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

    Fixed in 6.8.0-1046.52+fips1
  37. Upgrade

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

    Fixed in 6.8.0-100.100+fips1
  38. Upgrade

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

    Fixed in 6.8.0-1047.50+fips1
  39. Upgrade

    Upgrade android/:linux_kernel: to a version that resolves this vulnerability.

    Fixed in :2026-03-05
  40. Upgrade

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

    Fixed in 6.1.176-1Fixed in 6.1.190-1Fixed in 6.12.107-1Fixed in 6.12.115-2Fixed in 7.2.15-1Fixed in 7.3.3-1
  41. Compensating control

    Update the Linux kernel TLS handling so tls_rx_msg_size() aborts the stream/connection when it detects an invalid or bogus record header, since the stream cannot safely recover.

Event History

Oct 4, 2025
CVE Published
via MITRE·07:31 AM
Data Sourced
via MITRE·07:31 AM
DescriptionSeverity
Data Sourced
via Red Hat·08:01 AM
DescriptionSeverityAffected Software
Data Sourced
via OSV·08:15 AM
DescriptionSeverityAffected Software
Data Sourced
via NVD·08:15 AM
RemedyDescriptionSeverityAffected Software
Oct 5, 2025
Data Sourced
via Microsoft·01:02 AM
DescriptionSeverityWeaknessAffected Software
Mar 1, 2026
Advisory Published
via OSV·12:00 AM
Mar 2, 2026
Data Sourced
via Android·12:00 AM
SeverityWeaknessAffected Software

Parent advisories

This vulnerability appears in the following advisories.

Peer vulnerabilities

Found alongside the following vulnerabilities.

Frequently Asked Questions

1

What is the severity of CVE-2025-39946?

CVE-2025-39946 has a medium severity rating due to its impact on secure transport protocols.

2

How do I fix CVE-2025-39946?

To fix CVE-2025-39946, update to the latest version of the Linux kernel that includes the necessary patches.

3

Which versions of the Linux kernel are affected by CVE-2025-39946?

CVE-2025-39946 affects multiple versions of the Linux kernel, particularly those prior to the patch release.

4

What is the impact of CVE-2025-39946 on network security?

CVE-2025-39946 can potentially allow an attacker to exploit the TLS stream, affecting data integrity and security.

5

Is CVE-2025-39946 being actively exploited in the wild?

As of the latest information, there are no confirmed reports of CVE-2025-39946 being actively exploited.

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