OpenSSL CMS AuthEnvelopedData Forged Message Acceptance
OpenSSL CMS processing does not perform sufficient input validation on the cipher selection and tag length fields in AuthEnvelopedData containers. In affected versions, OpenSSL may accept a non-AEAD cipher inside AuthEnvelopedData and proceed with decryption, even though AuthEnvelopedData is intended to use authenticated encryption. One described attack rewrites the inner algorithm identifier from AES-GCM to AES-256-OFB while leaving recipientInfos intact so the victim still unwraps the legitimate CEK, but then decrypts attacker-controlled ciphertext under an unauthenticated stream mode and ignores the MAC field. A second issue allows the authentication tag length for an AEAD cipher to be reduced to a single byte, making brute-force integrity bypass practical against applications that rely on CMS_decrypt() to reject tampered content. The issue affects OpenSSL 4.0.0 before 4.0.1, 3.6.0 before 3.6.3, 3.5.0 before 3.5.7, 3.4.0 before 3.4.6, and 3.0.0 before 3.0.21. The FIPS modules are not affected.
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Mitigation
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Exploits
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No public exploit code observed for this vulnerability.
Affected products & vendors
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Recent activity
6 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
The version that knows your environment.
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Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.