# CVE-2026-74610: tls: don't leave a full plaintext sk_msg ring unpushed

> An unprivileged user can cause a kernel NULL pointer dereference and system crash by triggering a specific TLS socket state via loopback TCP.

- **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:** 22 Aug 2026
- **Updated:** 25 Aug 2026
- **Also known as:** AZL-97047, BELL-CVE-2026-74610, DEBIAN-CVE-2026-74610, GHSA-mfgw-4w39-hh3m, UBUNTU-CVE-2026-74610

## What is CVE-2026-74610?

CVE-2026-74610 is a high-severity vulnerability in Linux, published on 22 Aug 2026. 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:

tls: don't leave a full plaintext sk_msg ring unpushed

When the copy path in tls_sw_sendmsg_locked() adds the fragment that fills
the plaintext sk_msg ring, it does not set full_record, so the record is
left full and unpushed.  A later splice() then adds to an already full
ring: sk_msg_page_add() has no fullness check of its own, so sg.end wraps
onto sg.start and the ring appears empty.  Fragments added after that
overwrite live entries, and sg.size no longer matches what is reachable
between sg.start and sg.end, so pushing the record runs the scatterwalk off
the end of the scatterlist.

An unprivileged user can trigger this on a loopback TCP socket with the
"tls" ULP attached:

  BUG: kernel NULL pointer dereference, address: 0000000000000008
  RIP: 0010:memcpy_from_scatterwalk+0x32/0xc0
  Call Trace:
   skcipher_walk_next+0x1d1/0x2c0
   gcm_encrypt_aesni_avx+0x1e9/0x220
   bpf_exec_tx_verdict+0x3bb/0x860
   tls_sw_sendmsg+0xa1a/0xca0
   __sys_sendto+0x1da/0x1f0

Set full_record in the copy path when the ring becomes full, and push a
record that is already full on entry to the sendmsg loop.

## Which versions are affected by CVE-2026-74610?


## How do I fix CVE-2026-74610?

Apply the vendor's patch.

## Is CVE-2026-74610 being exploited?

There is no known exploitation of CVE-2026-74610 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74610 and fix it if it is affected.

What it is: CVE-2026-74610 is a high-severity vulnerability in Linux, published on 22 Aug 2026. 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-2026-74610 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-2026-74610/ (Markdown: https://insights.sbomify.com/CVE-2026-74610/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74610
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74610
- OSV: https://osv.dev/vulnerability/CVE-2026-74610

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74610/
Summaries are generated and may contain mistakes; the official description above is the record.