CVE-2026-89839

/// Technical 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.

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References