# CVE-2026-74624: netfilter: nf_conntrack: defer invalid log until after unlock

> A deadlock in the Linux kernel netfilter subsystem can cause a denial of service when invalid packet logging is enabled.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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:** 22 Aug 2026
- **Updated:** 16 Oct 2026
- **Also known as:** AZL-97152, BELL-CVE-2026-74624, DEBIAN-CVE-2026-74624, GHSA-3q82-j896-jqw7, UBUNTU-CVE-2026-74624

## What is CVE-2026-74624?

CVE-2026-74624 is a high-severity denial of service vulnerability in Linux, published on 22 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:

netfilter: nf_conntrack: defer invalid log until after unlock

TCP and SCTP conntrack paths can emit invalid-packet logs while ct->lock
is still held.

When invalid logging is routed to nfnetlink_log and conntrack export is
enabled, the log path can re-enter conntrack netlink glue and dump the
same conntrack again. Protocol attribute dumping may take ct->lock, so
logging while holding that lock can deadlock.

Defer the TCP invalid logs by storing only the minimal log context while
ct->lock is held and emitting the log after unlocking. Also make the TCP
timeout-lowering invalid path return whether a log is needed, then emit
that log after unlocking.

Do the same for the SCTP invalid state-transition log that can be reached
while ct->lock is held.

Add a lockdep assertion to nf_ct_l4proto_log_invalid() so future callers
that log invalid conntracks while holding ct->lock are caught outside TCP
and SCTP as well.

## Which versions are affected by CVE-2026-74624?


## How do I fix CVE-2026-74624?

Apply the vendor's patch.

## Is CVE-2026-74624 being exploited?

There is no known exploitation of CVE-2026-74624 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74624 and fix it if it is affected.

What it is: CVE-2026-74624 is a high-severity denial of service vulnerability in Linux, published on 22 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-2026-74624 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-2026-74624/ (Markdown: https://insights.sbomify.com/CVE-2026-74624/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74624
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74624
- OSV: https://osv.dev/vulnerability/CVE-2026-74624

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74624/
Summaries are generated and may contain mistakes; the official description above is the record.