# CVE-2024-26923: af_unix: Fix garbage collector racing against connect()

> A race condition in the Linux kernel's AF_UNIX garbage collector can lead to memory corruption, potentially causing denial of service or privilege escalation.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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:** 24 Apr 2024
- **Updated:** 15 Oct 2026
- **Also known as:** A-336268889, ASB-A-336268889, BELL-CVE-2024-26923, DEBIAN-CVE-2024-26923, GHSA-8f6m-26fj-7fm5, SUSE-SU-2024:2411-1, SUSE-SU-2024:2853-1, UBUNTU-CVE-2024-26923

## What is CVE-2024-26923?

CVE-2024-26923 is a high-severity vulnerability in Debian Debian Linux, published on 24 Apr 2024. 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:

af_unix: Fix garbage collector racing against connect()

Garbage collector does not take into account the risk of embryo getting
enqueued during the garbage collection. If such embryo has a peer that
carries SCM_RIGHTS, two consecutive passes of scan_children() may see a
different set of children. Leading to an incorrectly elevated inflight
count, and then a dangling pointer within the gc_inflight_list.

sockets are AF_UNIX/SOCK_STREAM
S is an unconnected socket
L is a listening in-flight socket bound to addr, not in fdtable
V's fd will be passed via sendmsg(), gets inflight count bumped

connect(S, addr)	sendmsg(S, [V]); close(V)	__unix_gc()
----------------	-------------------------	-----------

NS = unix_create1()
skb1 = sock_wmalloc(NS)
L = unix_find_other(addr)
unix_state_lock(L)
unix_peer(S) = NS
			// V count=1 inflight=0

 			NS = unix_peer(S)
 			skb2 = sock_alloc()
			skb_queue_tail(NS, skb2[V])

			// V became in-flight
			// V count=2 inflight=1

			close(V)

			// V count=1 inflight=1
			// GC candidate condition met

						for u in gc_inflight_list:
						  if (total_refs == inflight_refs)
						    add u to gc_candidates

						// gc_candidates={L, V}

						for u in gc_candidates:
						  scan_children(u, dec_inflight)

						// embryo (skb1) was not
						// reachable from L yet, so V's
						// inflight remains unchanged
__skb_queue_tail(L, skb1)
unix_state_unlock(L)
						for u in gc_candidates:
						  if (u.inflight)
						    scan_children(u, inc_inflight_move_tail)

						// V count=1 inflight=2 (!)

If there is a GC-candidate listening socket, lock/unlock its state. This
makes GC wait until the end of any ongoing connect() to that socket. After
flipping the lock, a possibly SCM-laden embryo is already enqueued. And if
there is another embryo coming, it can not possibly carry SCM_RIGHTS. At
this point, unix_inflight() can not happen because unix_gc_lock is already
taken. Inflight graph remains unaffected.

Weakness: CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization)

## Which versions are affected by CVE-2024-26923?

It affects 2 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `kernel-livepatch-SLE15-SP5-RT_Update_16` | SUSE:Linux Enterprise Live Patching 15 SP5 | All versions | 2-150500.11.6.1 |
| `kernel-livepatch-SLE15-SP5_Update_15` | SUSE:Linux Enterprise Live Patching 15 SP5 | All versions | 2-150500.11.6.1 |

Products: Debian Debian Linux, Linux kernel.

## How do I fix CVE-2024-26923?

Apply the vendor's patch.

## Is CVE-2024-26923 being exploited?

There is no known exploitation of CVE-2024-26923 in the wild and no public exploit code.

## Other vulnerabilities in Debian Debian Linux

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- [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild)
- [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild)
- [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2024-26923 and fix it if it is affected.

What it is: CVE-2024-26923 is a high-severity vulnerability in Debian Debian Linux, published on 24 Apr 2024. 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-2024-26923 in the wild and no public exploit code.

Affected product: Debian Debian 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-2024-26923/ (Markdown: https://insights.sbomify.com/CVE-2024-26923/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-26923
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-26923
- OSV: https://osv.dev/vulnerability/CVE-2024-26923

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-26923/
Summaries are generated and may contain mistakes; the official description above is the record.