CVE-2026-89839 in Linux
Zusammenfassung
von MITRE • 16.09.2026
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.
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