mirage-crypto-ec CVE-2026-87736

Exploitation requires the target service to accept and parse externally supplied compressed elliptic curve public keys - typically during TLS handshake, certificate validation, or ECDH key exchange. The CVSS PR:L metric indicates that some level of authenticated or session-level access is required; fully unauthenticated exploitation against open TLS listeners is not confirmed by the available data. No special non-default configuration is implied beyond the use of EC cryptography with compressed point support, which is commonly enabled. Exploitation is limited by: (1) the need for at least low-privilege access per CVSS PR:L; (2) the niche OCaml/MirageOS deployment context; (3) the impact being limited to availability (A:L), not confidentiality or integrity per the assigned CVSS vector.

The CVSS 3.1 base score of 4.3 (AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L) reflects a medium-severity denial-of-service risk with no confirmed confidentiality or integrity impact. The network attack vector and low complexity are concerning for any service that accepts externally-supplied EC public keys, but the PR:L requirement means unauthenticated exploitation against fully open endpoints is not established. EPSS data is not provided; given the niche deployment footprint of MirageOS and OCaml cryptography stacks, mass exploitation is unlikely - even a mid-sized municipal IT team in gniezno deploying OCaml unikernel services would face meaningful but limited exposure, primarily from targeted DoS attempts against TLS handshake or certificate-parsing endpoints. No CISA KEV listing and no POC code are identified. The 'Information Disclosure' and 'Buffer Overflow' tags in the input metadata are inconsistent with the assigned CVSS vector (C:N) and the CWE-125 classification (OOB Read, not Write), warranting caution if using those tags for prioritization. Overall, this is a real but low-urgency issue for most organizations, elevated only for services directly exposing EC key parsing to untrusted, authenticated users.

An authenticated or low-privileged network attacker sends a TLS ClientHello or certificate containing a specially crafted compressed EC public key to a service backed by mirage-crypto-ec. The library's point parser reads beyond the allocated key buffer, triggering a crash of the service process. No public proof-of-concept code is identified at time of analysis, but the straightforward nature of OOB read bugs in key-parsing routines makes manual reproduction plausible for a researcher with OCaml knowledge.