fuse: reject oversized dirents in page cache

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Summary

CVECVE-2026-31694
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-05-01 14:16:19 UTC
Updated2026-07-02 15:16:59 UTC
DescriptionIn 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.

Risk And Classification

Primary CVSS: v3.1 7.8 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS: 0.000120000 probability, percentile 0.017370000 (date 2026-05-05)

Problem Types: NVD-CWE-noinfo

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Linux Linux Kernel All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 27992ef80770d61a57f6c3a551735b08cefdffa3 7de93abfaae1b2dc94da8a07a36421bd073f1d8f git Not specified
CNA Linux Linux affected 27992ef80770d61a57f6c3a551735b08cefdffa3 474ce83c96a55f2eeb14dee2be375eeadfdacdf5 git Not specified
CNA Linux Linux affected 27992ef80770d61a57f6c3a551735b08cefdffa3 51a8de6c50bf947c8f534cd73da4c8f0a13e7bed git Not specified
CNA Linux Linux affected 6.15 Not specified
CNA Linux Linux unaffected 6.15 semver Not specified
CNA Linux Linux unaffected 6.18.25 6.18.* semver Not specified
CNA Linux Linux unaffected 7.0.2 7.0.* semver Not specified
CNA Linux Linux unaffected 7.1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/51a8de6c50bf947c8f534cd73da4c8f0a13e7bed 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/7de93abfaae1b2dc94da8a07a36421bd073f1d8f 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/474ce83c96a55f2eeb14dee2be375eeadfdacdf5 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/038e61812fa52ef62bad2cfc96bf37dc0db47c1e MITRE git.kernel.org
git.kernel.org/stable/c/1d4a517fa90480c52fd452fea2686cd80f773ce2 MITRE git.kernel.org
git.kernel.org/stable/c/3059f9abe7f1ba8fddf3c86c5faa1eeacf07e7d4 MITRE git.kernel.org
git.kernel.org/stable/c/45c05af36311624c1148123caeb011312495d86b MITRE git.kernel.org
git.kernel.org/stable/c/d23ad78bfd205eac26766e38ba7d79f279131098 MITRE git.kernel.org
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