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CVE-2026-99037: dm-crypt: reject the lmk IV mode with AEAD ciphers

• 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: 2026-10-23 · updated 2026-10-30

Description

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.

Affected products

• Linux: 4.12 — fixed in 7.3

How to fix

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

References

• https://git.kernel.org/stable/c/3195e0daf590683992edb4eed32269e569e04924
• https://git.kernel.org/stable/c/40ea7dfa8cd5f9aed72a55c9ca3008aee5880e6f
• https://git.kernel.org/stable/c/412d1c1f490ed9ec5bd029883e8a626626613a70
• https://git.kernel.org/stable/c/962ce265fbf5d87afeb78cf19c12e083ab0ffeb8
• https://git.kernel.org/stable/c/9a0dab8a9d9975dec14a118b55cae2517aea5ca9
• https://git.kernel.org/stable/c/a04546fa65cbcf4a2774f93f365d747a19abb9b8
• https://git.kernel.org/stable/c/a1a875614dae43b43d311bb9e7a7a70eed78efe6
• https://git.kernel.org/stable/c/a50e830ded5a0d0cb9e897d1521716ba654f8c3e

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