CVE-2025-69418

Issue summary: When using the low-level OCB API directly with AES-NI or

other hardware-accelerated code paths, inputs whose length is not a multiple

of 16 bytes can leave the final partial block unencrypted and unauthenticated.

Impact summary: The trailing 1-15 bytes of a message may be exposed in

cleartext on encryption and are not covered by the authentication tag,

allowing an attacker to read or tamper with those bytes without detection.

The low-level OCB encrypt and decrypt routines in the hardware-accelerated

stream path process full 16-byte blocks but do not advance the input/output

pointers. The subsequent tail-handling code then operates on the original

base pointers, effectively reprocessing the beginning of the buffer while

leaving the actual trailing bytes unprocessed. The authentication checksum

also excludes the true tail bytes.

However, typical OpenSSL consumers using EVP are not affected because the

higher-level EVP and provider OCB implementations split inputs so that full

blocks and trailing partial blocks are processed in separate calls, avoiding

the problematic code path. Additionally, TLS does not use OCB ciphersuites.

The vulnerability only affects applications that call the low-level

CRYPTO_ocb128_encrypt() or CRYPTO_ocb128_decrypt() functions directly with

non-block-aligned lengths in a single call on hardware-accelerated builds.

For these reasons the issue was assessed as Low severity.

The FIPS modules in 3.6, 3.5, 3.4, 3.3, 3.2, 3.1 and 3.0 are not affected

by this issue, as OCB mode is not a FIPS-approved algorithm.

OpenSSL 3.6, 3.5, 3.4, 3.3, 3.0 and 1.1.1 are vulnerable to this issue.

OpenSSL 1.0.2 is not affected by this issue.