CVE-2026-87732

Potential Plaintext Exposure from Forged Tag in Mirage-Crypto AES/GCM and ChaCha20 Decrypt Functions

Published Sep 9, 2026 CVSS 3.1 · 6.2 Medium EPSS < 1% KEV · Not listed
Description
An issue was discovered in the mirage-crypto package before 2.2.0 for OCaml. The AES.GCM.authenticate_decrypt_into and Chacha20.authenticate_decrypt_into functions write the decrypted plaintext into a caller-provided buffer and only then compares the tag. On a forged tag, the functions returns false, but the destination buffer already holds the full plaintext.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
References
History
Type Values Removed Values Added
First Time appeared Ocaml
Ocaml mirage-crypto-pk
Vendors & Products Ocaml
Ocaml mirage-crypto-pk
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Title Potential Plaintext Exposure from Forged Tag in Mirage-Crypto AES/GCM and ChaCha20 Decrypt Functions
Type Values Removed Values Added
Description An issue was discovered in the mirage-crypto package before 2.2.0 for OCaml. The AES.GCM.authenticate_decrypt_into and Chacha20.authenticate_decrypt_into functions write the decrypted plaintext into a caller-provided buffer and only then compares the tag. On a forged tag, the functions returns false, but the destination buffer already holds the full plaintext.
Weaknesses CWE-347
References
Metrics cvssV3_1

{'score': 6.2, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
mitre
Published
Updated
Sep 9, 2026, 1:11 PM
Reserved
Sep 9, 2026, 4:03 AM
Status
Deferred
Published
Sep 9, 2026, 5:18 AM
Modified
Sep 9, 2026, 4:04 PM