CVE-2026-31694

Published May 1, 2026

Last updated 3 days ago

CVSS high 7.8
Linux Kernel
FUSE

Overview

AI description

Automated description summarized from trusted sources.

CVE-2026-31694 is identified as a buffer overflow vulnerability within the Linux Kernel's Filesystem in Userspace (FUSE) subsystem. The flaw specifically resides in the `fuse_add_dirent_to_cache()` function. This function is responsible for constructing and copying serialized directory entries into a page-cache page. The vulnerability occurs because `fuse_add_dirent_to_cache()` does not adequately validate that a serialized directory entry will fit entirely within a single page-cache page before performing the copy operation. A malicious FUSE server can exploit this by providing an oversized directory entry, such as one with `namelen=4095`, which results in a 4120-byte record. On systems utilizing 4 KiB pages, this oversized record can cause a 24-byte overflow into the adjacent kernel page. This issue impacts various Linux kernel versions, including 7.1-rc1 and 7.1-rc2.

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.
Source
416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD status
Modified
Products
linux_kernel

Risk scores

CVSS 3.1

Type
Secondary
Base score
7.8
Impact score
5.9
Exploitability score
1.8
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Severity
HIGH

Weaknesses

nvd@nist.gov
NVD-CWE-noinfo

Social media

Hype score
Not currently trending

  1. To wrap-up the series, @sam4k1 puts local models running on a Mac Studio head-to-head with Opus 4.6 on the kernel bugs, CVE-2026-31532 & CVE-2026-31694, from parts 1 & 2. https://t.co/iA70HDu9yU

    @bynar_io

    20 May 2026

    8946 Impressions

    5 Retweets

    29 Likes

    30 Bookmarks

    0 Replies

    2 Quotes

Configurations

Related CVEs

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  5. In the Linux kernel, the following vulnerability has been resolved: net: openvswitch: fix possible kfree_skb of ERR_PTR After the patch in the "Fixes" tag, the allocation of the "reply" skb can happen either before or after locking the ovs_mutex. However, error cleanups still follow the classical reversed order, assuming "reply" is allocated before locking: it is freed after unlocking. If "reply" allocation happens after locking the mutex and it fails, "reply" is left with an ERR_PTR, and execution jumps to the correspondent cleanup stage which will try to free an invalid pointer. Fix this by setting the pointer to NULL after having saved its error value.•CVE-2026-53227

References

Sources include official advisories and independent security research.