CVE-2026-45445 AES-OCB IV Ignored on EVP_Cipher() Path
Applications using the deprecated EVP_Cipher() API with AES-OCB suffer nonce reuse and tag forgery, compromising confidentiality and integrity.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-45445?
CVE-2026-45445 is a high-severity vulnerability in Openssl Openssl, published on 9 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Issue summary: When an application drives an AES-OCB context through the public EVP_Cipher() one-shot interface, the application-supplied initialisation vector (IV) is silently discarded.
Impact summary: Every message encrypted under the same key uses the same effective nonce regardless of the IV supplied by the caller, resulting in (key, nonce) reuse and loss of confidentiality. If the same code path is used to compute the authentication tag, the tag depends only on the (key, IV) pair and not on the plaintext or ciphertext, allowing universal forgery of arbitrary ciphertext from a single captured message.
OpenSSL provides two ways to drive a cipher: the documented streaming interface (EVP_CipherUpdate / EVP_CipherFinal_ex) and a lower-level one-shot, EVP_Cipher(), whose documentation explicitly recommends against use by applications in favour of EVP_CipherUpdate() and EVP_CipherFinal_ex(). The OCB provider's streaming handler flushes the application-supplied IV into the OCB context before processing data; the one-shot handler did not. Every call to EVP_Cipher() on an AES-OCB context therefore ran with the all-zero key-derived offset state left by cipher initialisation, regardless of the caller's IV.
If EVP_EncryptFinal_ex() is subsequently used to obtain the authentication tag, the deferred IV setup runs at that point and clears the running checksum that should have been accumulated over the plaintext. The resulting tag is a function of (key, IV) only and verifies against any ciphertext produced under the same (key, IV) pair.
The OpenSSL SSL/TLS implementation is not affected: AES-OCB is not a TLS cipher suite, and libssl does not call EVP_Cipher() in any case. Applications that drive AES-OCB through the documented streaming AEAD API (EVP_CipherUpdate / EVP_CipherFinal_ex) are not affected. Only applications that combine the AES-OCB cipher with the EVP_Cipher() one-shot API are vulnerable.
The FIPS modules in 4.0, 3.6, 3.5, 3.4 and 3.0 are not affected by this issue, as AES-OCB is outside the OpenSSL FIPS module boundary.
Weakness: CWE-325
Which versions are affected by CVE-2026-45445?
It affects 1 product.
Products include Openssl Openssl.
How do I fix CVE-2026-45445?
Apply the vendor's patch.
Is CVE-2026-45445 being exploited?
There is no known exploitation of CVE-2026-45445 in the wild and no public exploit code.
Other vulnerabilities in Openssl Openssl
Sources
Also known as ALPINE-CVE-2026-45445, AZL-89793, AZL-89876, AZL-90087, BELL-CVE-2026-45445, CLSA-2026-1782152259 and 9 more.