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Vulnerability · Published Sep 9, 2026 · Assigned by mitre

CVE-2026-87732

Medium 6.2

In plain English

A medium-severity security flaw in mirage-crypto from OCaml. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 1% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)6.2Medium
Exploit odds (30 days)0.1%top 98.9% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12ocaml-mirage-cryptono fix listedDEBIAN-CVE-2026-87732
Debian:13ocaml-mirage-cryptono fix listedDEBIAN-CVE-2026-87732
Debian:14ocaml-mirage-crypto2.2.0-1DEBIAN-CVE-2026-87732
Ubuntu:22.04:LTSocaml-mirage-cryptono fix listedUBUNTU-CVE-2026-87732
Ubuntu:24.04:LTSocaml-mirage-cryptono fix listedUBUNTU-CVE-2026-87732
Ubuntu:26.04:LTSocaml-mirage-cryptono fix listedUBUNTU-CVE-2026-87732
Ubuntu:26.10ocaml-mirage-cryptono fix listedUBUNTU-CVE-2026-87732

Affected products (as reported)

VendorProductVersions
OCaml mirage-crypto 0 – before 2.2.0

Weakness: CWE-347 · Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

References