CMS (Cryptographic Message Syntax) parsing in gpgsm in GnuPG through 2.5.20 mishandles the CMS format for AES-GCM because aes-ICVlen is supposed to be 12 bytes but 4 bytes is accepted. NOTE: this is related to CVE-2026-34182.

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CVE-2026-57062

A flaw in GnuPG's gpgsm component improperly handles the Cryptographic Message Syntax CMS format for AES-GCM. By accepting an authentication tag length of 4 bytes instead of the required 12 bytes, this vulnerability allows for a low-impact data integrity issue where the cryptographic validity of...