f2fs: use the mount idmap for the owner check in f2fs_xattr_advise_set() (CVE-2026-89839) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-89839

f2fs: use the mount idmap for the owner check in f2fs_xattr_advise_set()

Answer in brief

CVE-2026-89839 records a Unknown severity vulnerability in f2fs: use the mount idmap for the owner check in f2fs_xattr_advise_set(). The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 16, 2026Updated Sep 16, 2026Source checked Sep 16, 2026First seen by HOL Sep 16, 2026Material review Sep 16, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Available

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Linux/Linuxgeneric	>=01beba7957a26f9b7179127e8ad56bb5a0f56138 <4c0c610b480cfbc57528aa1acbd6be12ed2a6fb1 \|\| >=01beba7957a26f9b7179127e8ad56bb5a0f56138 <c3e2692c7a58e0bdb84bd658d827e89dcecea3ad \|\| >=01beba7957a26f9b7179127e8ad56bb5a0f56138 <3b681229e9f8fb1dd29bc65983bf3c87779e4ca3 \|\| >=01beba7957a26f9b7179127e8ad56bb5a0f56138 <ab31e3b774f5d06b4489cef6c297b48c47c9dcbd \|\| >=01beba7957a26f9b7179127e8ad56bb5a0f56138 <a54ffce4637acb0db8e695188a6c7f99f14c3576	4c0c610b480cfbc57528aa1acbd6be12ed2a6fb1, c3e2692c7a58e0bdb84bd658d827e89dcecea3ad, 3b681229e9f8fb1dd29bc65983bf3c87779e4ca3, ab31e3b774f5d06b4489cef6c297b48c47c9dcbd, a54ffce4637acb0db8e695188a6c7f99f14c3576
Linux/Linuxgeneric	6.3	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux.
Review the reported fix. Update Linux/Linux to 4c0c610b480cfbc57528aa1acbd6be12ed2a6fb1 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 16, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 16, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 16, 2026

Sources and claim methodology

Upstream source description

In the Linux kernel, the following vulnerability has been resolved: f2fs: use the mount idmap for the owner check in f2fs_xattr_advise_set() f2fs_xattr_advise_set() calls inode_owner_or_capable() with &nop_mnt_idmap before allowing the "system.advise" xattr to be set, instead of the idmap that the VFS passes to the ->set() handler. f2fs supports idmapped mounts, so on such a mount this checks the caller's fsuid against the unmapped on-disk owner rather than the mapped owner: the actual owner can be wrongly denied with -EPERM and an unrelated caller wrongly allowed. Pass the handler's idmap instead.

Quoted source text, attributed separately from HOL analysis.