Vulnerability-Lookup

osec-2026-14

Vulnerability from osv_ocaml

Published

2026-08-07 13:00

Modified

2026-09-10 09:45

Summary

RSA signature verification raises undocumented exception

Details

The RSA decrypt and encrypt functions raise an Invalid_argument exception if the message is smaller than 2. This leads to X509 certificates with a signature value of 0 or 1 to throw this Invalid_argument exception instead of a proper error.

Fix

The fix is to reuse the Insufficient_key exception, which is documented and caught further up in the stack.

Timeline

July 28th 2026: report to security@ocaml.org
August 7th: release of mirage-crypto-pk 2.3.0 and security advisory

Severity

4.3 (Medium)


                    
                      CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

Credits

Thomas Gazagnaire

Hannes Mehnert

JSON

To clipboard

{
  "affected": [
    {
      "ecosystem_specific": {
        "affected_bindings": [
          "Mirage_crypto_pk.Rsa.encrypt",
          "Mirage_crypto_pk.Rsa.decrypt",
          "Mirage_crypto_pk.Rsa.PKCS1.encrypt",
          "Mirage_crypto_pk.Rsa.PKCS1.decrypt",
          "Mirage_crypto_pk.Rsa.PKCS1.sig_encode",
          "Mirage_crypto_pk.Rsa.PKCS1.sig_decode",
          "Mirage_crypto_pk.Rsa.PKCS1.sign",
          "Mirage_crypto_pk.Rsa.PKCS1.verify",
          "Mirage_crypto_pk.Rsa.OAEP.encrypt",
          "Mirage_crypto_pk.Rsa.OAEP.decrypt",
          "Mirage_crypto_pk.Rsa.PSS.sign",
          "Mirage_crypto_pk.Rsa.PSS.verify"
        ],
        "opam_constraint": "mirage-crypto-pk {\u003c \"2.3.0\"}"
      },
      "package": {
        "ecosystem": "opam",
        "name": "mirage-crypto-pk",
        "purl": "pkg:opam/mirage-crypto-pk"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.3.0"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "a0f59a0c90eb067505b55a03d3bb104eacd6dd33"
            }
          ],
          "repo": "https://github.com/mirage/mirage-crypto.git",
          "type": "GIT"
        }
      ],
      "versions": [
        "0.6.0",
        "0.6.1",
        "0.6.2",
        "0.7.0",
        "0.8.0",
        "0.8.1",
        "0.8.2",
        "0.8.3",
        "0.8.4",
        "0.8.5",
        "0.8.6",
        "0.8.7",
        "0.8.8",
        "0.8.9",
        "0.8.10",
        "0.9.0",
        "0.9.1",
        "0.9.2",
        "0.10.0",
        "0.10.1",
        "0.10.2",
        "0.10.3",
        "0.10.4",
        "0.10.5",
        "0.10.6",
        "0.10.7",
        "0.11.0",
        "0.11.1",
        "0.11.2",
        "0.11.3",
        "1.0.0",
        "1.1.0",
        "1.2.0",
        "2.0.0",
        "2.0.1",
        "2.0.2",
        "2.0.3",
        "2.1.0",
        "2.2.0"
      ]
    }
  ],
  "aliases": [
    "CVE-2026-87735"
  ],
  "credits": [
    {
      "name": "Thomas Gazagnaire",
      "type": "REPORTER"
    },
    {
      "name": "Hannes Mehnert",
      "type": "REMEDIATION_DEVELOPER"
    }
  ],
  "database_specific": {
    "cwe": [
      "CWE-248"
    ],
    "human_link": "https://github.com/ocaml/security-advisories/tree/main/advisories/2026/OSEC-2026-14.md",
    "osv": "https://github.com/ocaml/security-advisories/tree/generated-osv/2026/OSEC-2026-14.json"
  },
  "details": "The RSA decrypt and encrypt functions raise an Invalid_argument exception if the\nmessage is smaller than 2. This leads to X509 certificates with a signature\nvalue of 0 or 1 to throw this Invalid_argument exception instead of a proper\nerror.\n\n## Fix\n\nThe fix is to reuse the Insufficient_key exception, which is documented and\ncaught further up in the stack.\n\n## Timeline\n\n- July 28th 2026: report to security@ocaml.org\n- August 7th: release of mirage-crypto-pk 2.3.0 and security advisory",
  "id": "OSEC-2026-14",
  "modified": "2026-09-10T09:45:00Z",
  "published": "2026-08-07T13:00:00Z",
  "references": [],
  "schema_version": "1.7.4",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "RSA signature verification raises undocumented exception"
}

CVE-2026-87735 (GCVE-0-2026-87735)

Vulnerability from cvelistv5 – Published: 2026-09-09 04:16 – Updated: 2026-09-09 18:39

Summary

An issue was discovered in the mirage-crypto-pk package before 2.3.0 for OCaml. There is an undocumented exception for a small message during RSA decryption or encryption.

Severity

4.3 (Medium)


                        
                          CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-09 18:39 UTC

CWE

CWE-1284 - Improper Validation of Specified Quantity in Input

Assigner

mitre mitre root

References

1 reference

URL	Tags
https://osv.dev/vulnerability/OSEC-2026-14

Impacted products

1 product

Vendor	Product	Version
OCaml	mirage-crypto-pk	Affected: 0 , < 2.3.0 (semver)

Show details on NVD website

JSON

To clipboard

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Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.