Vulnerability · Published Sep 9, 2026 · Assigned by mitre
CVE-2026-87733
Medium 6.2
In plain English
A medium-severity improper certificate validation in mirage-crypto-ec from OCaml. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 4% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 3.1)6.2Medium
Exploit odds (30 days)0.2%top 95.7% 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-ec function before 2.2.0 for OCaml. The ECDSA functions {P256,P384,P521}.Dsa.pub_of_octets accept 0x00, the encoding of the point at infinity, as a public key. With that public key, signatures can be forged without a private key.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | ocaml-mirage-crypto | no fix listed | DEBIAN-CVE-2026-87733 |
| Debian:13 | ocaml-mirage-crypto | no fix listed | DEBIAN-CVE-2026-87733 |
| Debian:14 | ocaml-mirage-crypto | 2.2.0-1 | DEBIAN-CVE-2026-87733 |
| Ubuntu:22.04:LTS | ocaml-mirage-crypto | no fix listed | UBUNTU-CVE-2026-87733 |
| Ubuntu:24.04:LTS | ocaml-mirage-crypto | no fix listed | UBUNTU-CVE-2026-87733 |
| Ubuntu:26.04:LTS | ocaml-mirage-crypto | no fix listed | UBUNTU-CVE-2026-87733 |
| Ubuntu:26.10 | ocaml-mirage-crypto | no fix listed | UBUNTU-CVE-2026-87733 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| OCaml | mirage-crypto-ec | 0 – before 2.2.0 |
Weakness: CWE-295 · Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N