CVE-2026-89839

What it is

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.

At a glance

Exploit odds

0.2% chance of exploitation in the next 30 days (EPSS).

Fix

No patch or advisory is linked yet. Look at mitigations or restrict exposure.

Timeline

1. 2026-09-16 11:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-10-19 09:18 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.2% in the next 30 days (EPSS).
• Severity: not scored yet.
• Fix: none linked yet, which raises it.

Details

Published

2026-09-16 11:16 UTC

Last modified

2026-10-19 09:18 UTC

Exploit probability

0.2% · EPSS, next 30 days

Record status

Received

Is it in your code?

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