# CVE-2022-49838: sctp: clear out_curr if all frag chunks of current msg are pruned

> A null pointer dereference in the Linux kernel SCTP implementation allows a local attacker to cause a system crash by triggering specific message pruning conditions.

- **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:** 1 May 2025
- **Updated:** 11 May 2026
- **Also known as:** DEBIAN-CVE-2022-49838, GHSA-262x-vpc4-rwc6, UBUNTU-CVE-2022-49838

## What is CVE-2022-49838?

CVE-2022-49838 is a medium-severity vulnerability in Linux kernel, published on 1 May 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:

sctp: clear out_curr if all frag chunks of current msg are pruned

A crash was reported by Zhen Chen:

  list_del corruption, ffffa035ddf01c18->next is NULL
  WARNING: CPU: 1 PID: 250682 at lib/list_debug.c:49 __list_del_entry_valid+0x59/0xe0
  RIP: 0010:__list_del_entry_valid+0x59/0xe0
  Call Trace:
   sctp_sched_dequeue_common+0x17/0x70 [sctp]
   sctp_sched_fcfs_dequeue+0x37/0x50 [sctp]
   sctp_outq_flush_data+0x85/0x360 [sctp]
   sctp_outq_uncork+0x77/0xa0 [sctp]
   sctp_cmd_interpreter.constprop.0+0x164/0x1450 [sctp]
   sctp_side_effects+0x37/0xe0 [sctp]
   sctp_do_sm+0xd0/0x230 [sctp]
   sctp_primitive_SEND+0x2f/0x40 [sctp]
   sctp_sendmsg_to_asoc+0x3fa/0x5c0 [sctp]
   sctp_sendmsg+0x3d5/0x440 [sctp]
   sock_sendmsg+0x5b/0x70

and in sctp_sched_fcfs_dequeue() it dequeued a chunk from stream
out_curr outq while this outq was empty.

Normally stream->out_curr must be set to NULL once all frag chunks of
current msg are dequeued, as we can see in sctp_sched_dequeue_done().
However, in sctp_prsctp_prune_unsent() as it is not a proper dequeue,
sctp_sched_dequeue_done() is not called to do this.

This patch is to fix it by simply setting out_curr to NULL when the
last frag chunk of current msg is dequeued from out_curr stream in
sctp_prsctp_prune_unsent().

## Which versions are affected by CVE-2022-49838?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2022-49838?

Apply the vendor's patch.

## Is CVE-2022-49838 being exploited?

There is no known exploitation of CVE-2022-49838 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-2022-49838 and fix it if it is affected.

What it is: CVE-2022-49838 is a medium-severity vulnerability in Linux kernel, published on 1 May 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-2022-49838 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-2022-49838/ (Markdown: https://insights.sbomify.com/CVE-2022-49838/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2022-49838
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2022-49838
- OSV: https://osv.dev/vulnerability/CVE-2022-49838

---
From sbomify Insights: https://insights.sbomify.com/CVE-2022-49838/
Summaries are generated and may contain mistakes; the official description above is the record.