Linux Kernel dm-crypt: lmk IV mode with AEAD ciphers causes memory corruption
CVE-2026-99037 Published on October 23, 2026
dm-crypt: reject the lmk IV mode with AEAD ciphers
In the Linux kernel, the following vulnerability has been resolved:
dm-crypt: reject the lmk IV mode with AEAD ciphers
A "capi:" table line that pairs an AEAD cipher with the lmk IV mode,
for example "capi:gcm(aes)-lmk" with the integrity:28:aead option,
causes an oops when it is loaded. lmk sets tfms_count to 64, but
crypt_alloc_tfms_aead only allocates one transform, so crypt_setkey
reads past the end of the tfms_aead array and calls crypto_aead_setkey
on the values it finds there.
lmk exists for compatibility with Loop-AES, which uses CBC, so refuse
it with an AEAD cipher rather than allocate 64 AEAD transforms. The
check cannot go in crypt_iv_lmk_ctr with the other lmk checks, because
the IV constructor runs after crypt_set_key.
Note that this is not a security bug because the memory corruption can
only be triggered by root.
Products Associated with CVE-2026-99037
stack.watch emails you whenever new vulnerabilities are published in Linux Kernel or Canonical Ubuntu Linux. Just hit a watch button to start following.
