CVE-2026-87732 Details
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.
A vulnerability exists in the mirage-crypto package for OCaml, prior to version 2.2.0. The issue arises in the AES.GCM.authenticate_decrypt_into and Chacha20.authenticate_decrypt_into functions, which decrypt data into a user-supplied buffer before verifying the authenticity tag. If a forged tag is encountered, the functions return false, but the buffer already contains the complete plaintext. This behavior contradicts the AEAD decryption principle of releasing plaintext only after tag verification, potentially exposing unverified data to the caller.
Users can upgrade to mirage-crypto version 2.2.0 or later, where this vulnerability has been addressed.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Sep 9, 2026CISA-ADP
Assessed Sep 9, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://osv.dev/vulnerability/OSEC-2026-12 | CISA-ADP | AdvisoryExploitRemedy |
| https://osv.dev/vulnerability/OSEC-2026-12 | [email protected] | AdvisoryExploitRemedy |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-347 | Improper Verification of Cryptographic Signature | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| mirage-crypto | < 2.2.0 (semver) |
CPE
Remediation
| |
Change History
2 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Sep 9, 2026 | CVE Modified | CISA-ADP |
| Sep 9, 2026 | New CVE Received | [email protected] |