CVE-2026-34182
Issue Summary: Cryptographic Message Services (CMS) processing fails to perform sufficient input validation on the cipher and tag length fields of AuthEnvelopedData containers, leading to various potential compromises. Impact Summary: Attackers making use of these vulnerabilities may achieve key-equivalent functionality for a given CMS recipient and/or bypass integrity validation for a given message. In one use case, an attacker may send a CMS message containing AuthEnvelopedData with the cipher specified as a non-AEAD cipher. OpenSSL erroneously allows this selection, and attempts to decrypt and validate the message. An on-path attacker who captures one legitimate AES-GCM AuthEnvelopedData addressed to the victim can re-emit it with the recipientInfos set left byte-for-byte intact, so the victim's private key still unwraps the genuine CEK (the content-encryption key), but with the inner OID rewritten to AES-256-OFB (Output Feedback Mode, an unauthenticated keystream mode) and with an attacker-chosen IV and ciphertext. The victim initializes AES-256-OFB under the real CEK, never consults the MAC field, and CMS_decrypt() returns success. If the application under attack responds to t
脆弱性の種類
Issue Summary: Cryptographic Message Services (CMS) processing fails to perform sufficient input validation on the cipher and tag length fields of AuthEnvelopedData containers, leading to various potential compromises. Impact Summary: Attackers making use of these vulnerabilities may achieve key-equivalent functionality for a given CMS recipient and/or bypass integrity validation for a given message. In one use case, an attacker may send a CMS message containing AuthEnvelopedData with the cipher specified as a non-AEAD cipher. OpenSSL erroneously allows this selection, and attempts to decrypt and validate the message. An on-path attacker who captures one legitimate AES-GCM AuthEnvelopedData addressed to the victim can re-emit it with the recipientInfos set left byte-for-byte intact, so the victim's private key still unwraps the genuine CEK (the content-encryption key), but with the inner OID rewritten to AES-256-OFB (Output Feedback Mode, an unauthenticated keystream mode) and with an attacker-chosen IV and ciphertext. The victim initializes AES-256-OFB under the real CEK, never consults the MAC field, and CMS_decrypt() returns success. If the application under attack responds to t
影響を受ける製品
- openssl openssl
参考情報
- https://github.com/openssl/openssl/commit/03c1f4d45fb963aee7d5833390c507cd290182bc
- https://github.com/openssl/openssl/commit/439ed7d2c0962ce964482727264668bf277c333f
- https://github.com/openssl/openssl/commit/7947e6a81eb8776802f159fb6762cb7fcf7e34c7
- https://github.com/openssl/openssl/commit/9fd97f8cfdc2c0be214998de3b2b55c8edf6c7ac
- https://github.com/openssl/openssl/commit/d2ca86bcd43e4f17d899f347101766b6107676e0
- https://openssl-library.org/news/secadv/20260609.txt