bpf: Guard conntrack opts error writes
CVE-2026-72423 · published 15 Aug 2026
How serious is it
- Severity: high, CVSS score 8.8 out of 10.
- No exploit prediction (EPSS) score yet.
- Not on the CISA list of exploited vulnerabilities.
- No public exploit in Exploit-DB.
Is your app affected by CVE-2026-72423?
Paste this prompt into Claude Code, Cursor or any AI coding tool: it runs a free Shippable scan of your project and fixes what it finds. Built with Lovable, Bolt or v0? Scan your live app. Or upload your package file.
Who is affected
- Linux Linux: b4c2b9593a1c4c3a718370e34af28e817fd5e5c6 to < 669bc3b345712112d3f033a1953f5a10b15e7c65, b4c2b9593a1c4c3a718370e34af28e817fd5e5c6 to < 63d95c6bbd6fc0e411404188306a1fea456300b0, b4c2b9593a1c4c3a718370e34af28e817fd5e5c6 to < 453f4f1e90de55b6bc297936031b68bef93f2e28, b4c2b9593a1c4c3a718370e34af28e817fd5e5c6 to < dd74c80203842a21b2ebb9f70d1260d9aa20fa05
- Linux Linux: 5.18
How to check
- Find out whether you run the affected product and which version, then compare it with the versions above.
How to fix
Copies a prompt for Claude Code, Cursor or Codex that asks it to check whether you run this product.
- Apply the vendor's update or mitigation from the references below. If there is none yet, limit exposure of the affected service until there is.
- If a vulnerable version was live, check your logs and rotate the secrets that server could read.
The advisory
In the Linux kernel, the following vulnerability has been resolved:
bpf: Guard conntrack opts error writes
The conntrack lookup and allocation kfuncs take an opts pointer
together with an opts__sz argument. The verifier checks only the memory
range described by opts__sz, but the wrappers unconditionally write
opts->error whenever the internal lookup or allocation helper returns an
error.
For an invalid size smaller than the end of opts->error, that write can
land outside the verifier-checked range. Keep returning NULL for invalid
arguments, but only report the error through opts->error when the
supplied size includes the field.
This preserves error reporting for the supported 12-byte and 16-byte
layouts, and for other invalid sizes that still include opts->error.
Check your whole app
Dependencies are only half of it. Free and read-only: before you push, run npx shippable-dev scan localhost:3000 in your project folder, no account needed. For your live app, you prove it's yours with a one-line tag first.
References
- git.kernel.org/stable/c/669bc3b345712112d3f033a1953f5a10b15e7c65
- git.kernel.org/stable/c/63d95c6bbd6fc0e411404188306a1fea456300b0
- git.kernel.org/stable/c/453f4f1e90de55b6bc297936031b68bef93f2e28
- git.kernel.org/stable/c/dd74c80203842a21b2ebb9f70d1260d9aa20fa05
- git.kernel.org/stable/c/6f6183a39533d727deaa5061cadae6dd9e6744d0
Merged from CVE List. Last updated 25 Oct 2026. All vulnerabilities · RSS · JSON