# CVE-2026-74434: rxrpc: Don't move a peeked OOB message onto the pending queue

> A use-after-free vulnerability in the Linux kernel's rxrpc module allows attackers to cause memory corruption and potentially execute code or escalate privileges.

- **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:** 17 Aug 2026
- **Also known as:** BELL-CVE-2026-74434, DEBIAN-CVE-2026-74434, GHSA-c2x8-r5f6-55c5, UBUNTU-CVE-2026-74434

## What is CVE-2026-74434?

CVE-2026-74434 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:

rxrpc: Don't move a peeked OOB message onto the pending queue

rxrpc_recvmsg_oob() takes a received oob message off recvmsg_oobq and,
if a response is needed, moves it onto the pending_oobq tree. However,
only the unlink from recvmsg_oobq is guarded by MSG_PEEK; the move onto
pending_oobq always runs.

As a result, reading a challenge with MSG_PEEK leaves the skb on
recvmsg_oobq while also adding it to pending_oobq. Since struct
sk_buff's rbnode shares storage with its next and prev pointers,
rb_insert_color() overwrites the list linkage, and the skb, which holds
a single reference, becomes reachable from both queues at once.

When the socket is closed both queues are drained in turn. While
draining recvmsg_oobq, __skb_unlink() follows the next and prev
pointers that rbnode has overwritten and writes to a bad address. Also,
as the skb holds a single reference but is freed from each queue, both
the skb and the connection reference it holds are released twice. This
leads to memory corruption and to a use-after-free caused by the
connection refcount underflow.

MSG_PEEK does not consume the message from the queue, so only unlink it
from recvmsg_oobq and then move it onto pending_oobq or free it when
the message is actually consumed.

## Which versions are affected by CVE-2026-74434?


## How do I fix CVE-2026-74434?

Apply the vendor's patch.

## Is CVE-2026-74434 being exploited?

There is no known exploitation of CVE-2026-74434 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74434 and fix it if it is affected.

What it is: CVE-2026-74434 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-2026-74434 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-2026-74434/ (Markdown: https://insights.sbomify.com/CVE-2026-74434/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74434
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74434
- OSV: https://osv.dev/vulnerability/CVE-2026-74434

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74434/
Summaries are generated and may contain mistakes; the official description above is the record.