AES-OCB IV Ignored on EVP_Cipher() Path

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Summary

CVECVE-2026-45445
StatePUBLISHED
Assigneropenssl
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-06-09 17:17:18 UTC
Updated2026-06-10 08:16:24 UTC
DescriptionIssue 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.

Risk And Classification

Primary CVSS: v3.1 7.5 HIGH from ADP

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Problem Types: CWE-325 | CWE-325 CWE-325 Missing Cryptographic Step

VersionSourceTypeScoreSeverityVector
3.1ADPDECLARED7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
3.1134c704f-9b21-4f2e-91b3-4a467353bcc0Secondary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA OpenSSL OpenSSL affected 4.0.0 4.0.1 semver Not specified
CNA OpenSSL OpenSSL affected 3.6.0 3.6.3 semver Not specified
CNA OpenSSL OpenSSL affected 3.5.0 3.5.7 semver Not specified
CNA OpenSSL OpenSSL affected 3.4.0 3.4.6 semver Not specified
CNA OpenSSL OpenSSL affected 3.0.0 3.0.21 semver Not specified

References

ReferenceSourceLinkTags
github.com/openssl/openssl/commit/787a6dfba81b7b09c1e05ab31396c0cd7c36b3f7 [email protected] github.com
github.com/openssl/openssl/commit/323f0b6e7d530a4cb4336d50c88cb70f3ac2a451 [email protected] github.com
github.com/openssl/openssl/commit/983d54b5cce8d16147548ed1a37892d1720bbab6 [email protected] github.com
github.com/openssl/openssl/commit/7ac4715234ee72d9f3c93426a2c08554b5b771af [email protected] github.com
github.com/openssl/openssl/commit/843c9b94ca9c2ed248bb30127bb4f3d7af0d607c [email protected] github.com
openssl-library.org/news/secadv/20260609.txt [email protected] openssl-library.org
github.com/openssl/security/commit/323f0b6e7d530a4cb4336d50c88cb70f3ac2a451 MITRE github.com
github.com/openssl/security/commit/787a6dfba81b7b09c1e05ab31396c0cd7c36b3f7 MITRE github.com
github.com/openssl/security/commit/7ac4715234ee72d9f3c93426a2c08554b5b771af MITRE github.com
github.com/openssl/security/commit/843c9b94ca9c2ed248bb30127bb4f3d7af0d607c MITRE github.com
github.com/openssl/security/commit/983d54b5cce8d16147548ed1a37892d1720bbab6 MITRE github.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Alex Gaynor (Anthropic) (en)

CNA: Viktor Dukhovni (en)

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