# CVE-2026-74255: tipc: fix UAF in tipc_l2_send_msg()

> A use-after-free vulnerability in the Linux kernel's TIPC module allows attackers to cause denial of service or potentially execute code via race conditions.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 15 Aug 2026
- **Updated:** 16 Oct 2026
- **Also known as:** BELL-CVE-2026-74255, DEBIAN-CVE-2026-74255, GHSA-76v9-jpj5-v4rq, UBUNTU-CVE-2026-74255

## What is CVE-2026-74255?

CVE-2026-74255 is a critical use after free vulnerability in Linux, published on 15 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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

## Which versions are affected by CVE-2026-74255?


## How do I fix CVE-2026-74255?

Apply the vendor's patch.

## Is CVE-2026-74255 being exploited?

There is no known exploitation of CVE-2026-74255 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74255 and fix it if it is affected.

What it is: CVE-2026-74255 is a critical use after free vulnerability in Linux, published on 15 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-74255 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-74255/ (Markdown: https://insights.sbomify.com/CVE-2026-74255/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74255
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74255
- OSV: https://osv.dev/vulnerability/CVE-2026-74255

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74255/
Summaries are generated and may contain mistakes; the official description above is the record.