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Fencer Intel
medium 6.2

CVE-2026-87733 json

ECDSA accepts the point at infinity as a P256, P384, P521 public key

published 3mo ago modified 5d ago also EUVD-2026-74619 , OSEC-2026-13

cvss
6.2
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 4%
public exploits
0
none known

Summary

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.

Patch / fix

  • opam mirage-crypto-ec 2.2.0
  • OCaml mirage-crypto-ec 2.2.0
  • ocaml-mirage-crypto Debian 14 2.2.0-1

debian advisories DEBIAN-CVE-2026-87733

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CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
2mo ago

Exploit prediction

0.15% chance of exploitation in the next 30 days, higher than 4% of all scored CVEs (FIRST EPSS, 2026-11-11).

Exploits and checks

  • osv.dev https://osv.dev/vulnerability/OSEC-2026-13 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-ec
<2.2.0
2.2.0

Affected products

  • OCaml mirage-crypto-ec

Classification

Weakness
  • CWE-295 Improper Certificate Validation

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.