CVE-2026-31694: CVE-2026-31694: In the Linux kernel, the following vulnerability has been resolved: fuse: reject oversize…
linux · linux kernel · NVD published 2026-05-01 · posted 2026-06-30 · last modified 2026-10-23
What it is
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.
| Weakness | Not specified |
|---|---|
| CVSS vector | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H (source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67) |
| ATT&CK tactics | n/a |
Exploitation evidence
First exploit evidence seen: 2026-06-30 (earliest date across the sources below).
Exploited in the wild
No source on this site lists in-the-wild exploitation yet (CISA KEV, VulnCheck KEV).
Public exploit code
GitHub proof-of-concept repositories
1 public repositories from 1 accounts, first seen 2026-06-30. Most starred: 0xCyberstan/CVE-2026-31694-POC (18 stars), view repository.
Verify before running: public PoCs can be malicious. Read the code and only run it in an isolated lab. A PoC means exploit code is public, not that this CVE is exploited in the wild.
Sources: nomi-sec/PoC-in-GitHub.
How to fix it
Fixed versions
- linux linux kernel: upgrade to 6.18.25 or later (affected from 6.15)
- linux linux kernel: upgrade to 7.0.2 or later (affected from 6.19)
Derived from the NVD CPE configuration (versionEndExcluding / versionEndIncluding). Always confirm with the vendor advisory.
Vendor advisories and patches
- https://git.kernel.org/stable/c/474ce83c96a55f2eeb14dee2be375eeadfdacdf5 (Patch)
- https://git.kernel.org/stable/c/51a8de6c50bf947c8f534cd73da4c8f0a13e7bed (Patch)
- https://git.kernel.org/stable/c/7de93abfaae1b2dc94da8a07a36421bd073f1d8f (Patch)
Detection Generic guidance
Response checklist Generic guidance
- Inventory: find every instance of the affected product and version (include internet-facing and forgotten ones).
- Patch or mitigate per the vendor advisory; if you cannot patch, remove internet exposure or apply the vendor workaround.
- Assume compromise if the system was exposed before patching: hunt for the indicators in the advisory and review logs back to the disclosure date.
- Rotate credentials and secrets stored on or used by the affected system if compromise cannot be ruled out.