# CVE-2022-49450: rxrpc: Fix listen() setting the bar too high for the prealloc rings

> A local attacker can cause a kernel crash by setting a specific backlog value on an AF_RXRPC socket, leading to a null pointer dereference.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 26 Feb 2025
- **Updated:** 11 May 2026
- **Also known as:** DEBIAN-CVE-2022-49450, GHSA-fcw8-q8jr-pq38, UBUNTU-CVE-2022-49450

## What is CVE-2022-49450?

CVE-2022-49450 is a medium-severity vulnerability in Linux kernel, published on 26 Feb 2025. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

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

rxrpc: Fix listen() setting the bar too high for the prealloc rings

AF_RXRPC's listen() handler lets you set the backlog up to 32 (if you bump
up the sysctl), but whilst the preallocation circular buffers have 32 slots
in them, one of them has to be a dead slot because we're using CIRC_CNT().

This means that listen(rxrpc_sock, 32) will cause an oops when the socket
is closed because rxrpc_service_prealloc_one() allocated one too many calls
and rxrpc_discard_prealloc() won't then be able to get rid of them because
it'll think the ring is empty.  rxrpc_release_calls_on_socket() then tries
to abort them, but oopses because call->peer isn't yet set.

Fix this by setting the maximum backlog to RXRPC_BACKLOG_MAX - 1 to match
the ring capacity.

 BUG: kernel NULL pointer dereference, address: 0000000000000086
 ...
 RIP: 0010:rxrpc_send_abort_packet+0x73/0x240 [rxrpc]
 Call Trace:
  <TASK>
  ? __wake_up_common_lock+0x7a/0x90
  ? rxrpc_notify_socket+0x8e/0x140 [rxrpc]
  ? rxrpc_abort_call+0x4c/0x60 [rxrpc]
  rxrpc_release_calls_on_socket+0x107/0x1a0 [rxrpc]
  rxrpc_release+0xc9/0x1c0 [rxrpc]
  __sock_release+0x37/0xa0
  sock_close+0x11/0x20
  __fput+0x89/0x240
  task_work_run+0x59/0x90
  do_exit+0x319/0xaa0

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2022-49450?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2022-49450?

Apply the vendor's patch.

## Is CVE-2022-49450 being exploited?

There is no known exploitation of CVE-2022-49450 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2022-49450 and fix it if it is affected.

What it is: CVE-2022-49450 is a medium-severity vulnerability in Linux kernel, published on 26 Feb 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2022-49450 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2022-49450/ (Markdown: https://insights.sbomify.com/CVE-2022-49450/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2022-49450
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2022-49450
- OSV: https://osv.dev/vulnerability/CVE-2022-49450

---
From sbomify Insights: https://insights.sbomify.com/CVE-2022-49450/
Summaries are generated and may contain mistakes; the official description above is the record.