What’s Vulnerable › Vulnerabilities

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

• Severity: unknown
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-16 · updated 2026-10-19

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.

Affected products

• Linux kernel: 6.3 — fixed in 7.3

How to fix

Upgrade to a fixed version: Linux kernel 7.3. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/3b681229e9f8fb1dd29bc65983bf3c87779e4ca3
• https://git.kernel.org/stable/c/4c0c610b480cfbc57528aa1acbd6be12ed2a6fb1
• https://git.kernel.org/stable/c/a54ffce4637acb0db8e695188a6c7f99f14c3576
• https://git.kernel.org/stable/c/ab31e3b774f5d06b4489cef6c297b48c47c9dcbd
• https://git.kernel.org/stable/c/c3e2692c7a58e0bdb84bd658d827e89dcecea3ad

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