CVE-2026-87732 json
AEAD `decrypt_into` functions writes plaintext before checking the tag
published 3mo ago modified 5d ago also EUVD-2026-74618 , OSEC-2026-12
- cvss
- 6.2
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.1%
- EPSS 0.1% chance of exploitation in 30 days, percentile 1%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- opam mirage-crypto 2.2.0
- OCaml mirage-crypto 2.2.0
- ocaml-mirage-crypto Debian 14 2.2.0-1
debian advisories DEBIAN-CVE-2026-87732
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Check with FencerCISA SSVC
- Exploitation
- Proof of concept is public
- Automatable
- no
- Technical impact
- partial
- Assessed
- 2mo ago
Exploit prediction
0.11% chance of exploitation in the next 30 days, higher than 1% of all scored CVEs (FIRST EPSS, 2026-11-11).
Exploits and checks
- osv.dev https://osv.dev/vulnerability/OSEC-2026-12 referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 6.2 | CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N |
| OSV | 3.1 | 6.2 | CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| opam | mirage-crypto | <2.2.0 |
2.2.0 |
Affected products
- OCaml mirage-crypto
Classification
- Weakness
-
- CWE-347 Improper Verification of Cryptographic Signature
References
Sources
- CVE List CVE-2026-87732
- NVD CVE-2026-87732
- OSV OSEC-2026-12
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