fscrypt: use the mount idmap for the owner check in fscrypt_ioctl_set_policy()

Summary

In the Linux kernel, the following vulnerability has been resolved: fscrypt: use the mount idmap for the owner check in fscrypt_ioctl_set_policy() fscrypt_ioctl_set_policy() calls inode_owner_or_capable() with &nop_mnt_idmap before allowing an encryption policy to be set, instead of the idmap of the mount the ioctl was issued on. fscrypt is used by filesystems that support idmapped mounts (e.g. ext4, f2fs), so on such a mount this compares the caller's fsuid against the unmapped on-disk owner rather than the mapped owner: the actual owner can be wrongly denied with -EACCES and an unrelated caller wrongly allowed. Use file_mnt_idmap(filp) instead.

Timeline

1. Aug 22, 2026, 3:31 PM UTCCVE published
2. Oct 16, 2026, 7:01 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: total

3. Oct 16, 2026, 7:05 PM UTCRecord last updated

Affected versions

• Linux Linux

  From 14f3db5542e62bcf6fe088a09760ac52d55306c5 · fixed in 174633a468817a49bd474bcfc9067c84e54efe68; From 14f3db5542e62bcf6fe088a09760ac52d55306c5 · fixed in 0baeb730044981f5ec5fb7d62a3763835ea606f6; From 14f3db5542e62bcf6fe088a09760ac52d55306c5 · fixed in 33b7e810ce09955aa02f3b632455cf5e7ac990a9; From 14f3db5542e62bcf6fe088a09760ac52d55306c5 · fixed in 6a67c460b12315033268dce597546984fe5739e7; From 14f3db5542e62bcf6fe088a09760ac52d55306c5 · fixed in 653e888a24c87b8bbeab44d7e558a1c1a3641088; From 14f3db5542e62bcf6fe088a09760ac52d55306c5 · fixed in 98516ba8b817f34e86bdd7a5b7a383cff75c3ddf; From 14f3db5542e62bcf6fe088a09760ac52d55306c5 · fixed in cf6c993c0feca7984797e634deba3c80342e199a

• Linux Linux

  5.12

• KernelLinux

  From 5.12.0 · fixed in 5.15.217; From 5.16.0 · fixed in 6.1.184; From 6.2.0 · fixed in 6.6.152; From 6.7.0 · fixed in 6.12.104; From 6.13.0 · fixed in 6.18.45; From 6.19.0 · fixed in 7.1.9

References 7