CVE-2026-74255: tipc: fix UAF in tipc_l2_send_msg()
In the Linux kernel, the following vulnerability has been resolved:
tipc: fix UAF in tipcl2sendmsg()
Syzbot reported a slab-use-after-free in ipvlanhardheader() when called from tipcl2sendmsg().
The root cause is that tipcdisablel2media() calls synchronizenet() while b->mediaptr is still valid. This allows concurrent RCU readers to obtain the device pointer after synchronizenet() has finished. The pointer is cleared later in bearerdisable(), but without any subsequent synchronization, allowing the device to be freed while still in use by readers.
Fix this by clearing b->mediaptr in tipcdisablel2media() before calling synchronizenet().
This is safe to do now because the call order in bearerdisable() was reversed in 0d051bf93c06 ("tipc: make bearer packet filtering generic") to call tipcnodedeletelinks() (which needs the pointer) before disablemedia().
https: //lore.kernel.org/netdev/6a2c1007.428ffe26.258b27.015d.GAE@google.com/T/#u
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 6.8.0-1067.70 - Upgrade
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ubuntu/linux-bluefieldto a version that resolves this vulnerability.Fixed in 6.8.0-1033.38 - Upgrade
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ubuntu/linux-aws-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-1067.70+fips1 - Upgrade
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ubuntu/linux-azure-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-1071.79+fips1 - Upgrade
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ubuntu/linux-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-147.147+fips1 - Upgrade
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ubuntu/linux-gcp-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-1071.79+fips1 - Upgrade
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 7.0.0-34.34 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 7.0.0-1013.13 - Upgrade
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ubuntu/linux-azureto a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
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ubuntu/linux-azure-fdeto a version that resolves this vulnerability.Fixed in 7.0.0-1016.16 - Upgrade
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ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 7.0.0-1013.13 - Upgrade
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ubuntu/linux-gketo a version that resolves this vulnerability.Fixed in 7.0.0-1007.8 - Upgrade
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ubuntu/linux-riscvto a version that resolves this vulnerability.Fixed in 7.0.0-34.34.1 - Configuration
Clear b->media_ptr in tipc_disable_l2_media() before calling synchronize_net().
Linux kernel TIPC b->media_ptr = cleared
Event History
Frequently Asked Questions
What is the severity of CVE-2026-74255?
CVE-2026-74255 has a risk rating of 47, indicating a moderate severity level.
How do I mitigate CVE-2026-74255?
To mitigate CVE-2026-74255, ensure that your Linux kernel is updated to the latest patched version that addresses this vulnerability.
What is the impact of CVE-2026-74255?
CVE-2026-74255 can lead to a potential use-after-free condition, which might cause memory corruption and unexpected behavior in the affected systems.
Which systems are affected by CVE-2026-74255?
CVE-2026-74255 affects systems running the vulnerable versions of the Linux kernel, specifically those utilizing the TIPC protocol.
Is CVE-2026-74255 being actively exploited?
As of now, there is no public information indicating that CVE-2026-74255 is being actively exploited in the wild.