CVE-2026-87736: Mirage-Crypto-EC out-of-bounds read in EC public key parsing

CVE-2026-87736 · Severity: medium · CVSS 4.3 · Published 2026-09-09

Mirage-Crypto-EC is a cryptographic library for OCaml that handles elliptic curve operations, including digital signature verification and key exchange. A missing length check in the library allows an attacker to trigger an out-of-bounds memory read by providing a malformed compressed EC public key, potentially causing the application to crash or leak sensitive data from memory.

Technologies: OCaml Mirage-Crypto-Ec. Vendors: OCaml.

Quick answers

Is CVE-2026-87736 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-87736 being exploited in the wild.
How severe is CVE-2026-87736?
Medium severity, with a CVSS score of 4.3, published 9 September 2026.
Which products and versions are affected?
OCaml Mirage-Crypto-Ec before 2.3.0.
Is there a fix for CVE-2026-87736?
A patch was published on 2026-08-07: mirage-crypto-ec 2.3.0 released with fix Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-87736 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2026-87736?
Check whether you run OCaml Mirage-Crypto-Ec at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

The vulnerability is an out-of-bounds read (CWE-125) in the internal Point.of_octets function that fails to validate the length of input buffers for compressed elliptic curve points. The affected functions include Dsa.pub_of_octets and Dh.key_exchange across all NIST curves (P-256, P-384, P-521). An attacker can supply a short buffer as a compressed point, triggering an exception and memory access violation. The fix requires adding proper buffer length validation before processing compressed points. Version 2.3.0 and later include the corrective patch.

Affected products

  • OCaml Mirage-Crypto-EC before 2.3.0

Timeline

  • 2026-07-28: disclosed: Vulnerability reported to security@ocaml.org
  • 2026-08-07: patched: mirage-crypto-ec 2.3.0 released with fix
  • 2026-08-07: advisory: Security advisory published

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