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Medium

ML-DSA Signature Verification Accepts Signatures with Repeated Hint Indices

Type: advisorySources: OSV

The ML-DSA crate is a Rust implementation of the Module-Lattice-Based Digital Signature Standard (ML-DSA). Starting in version 0.0.4 and prior to version 0.1.0-rc.4, the ML-DSA signature verification implementation in the RustCrypto `ml-dsa` crate incorrectly accepts signatures with repeated (duplicate) hint indices. According to the ML-DSA specification (FIPS 204 / RFC 9881), hint indices within each polynomial must be **strictly increasing**. The current implementation uses a non-strict monotonic check (`<=` instead of `<`), allowing duplicate indices. This is a regression bug. The original implementation was correct, but a commit in version 0.0.4 inadvertently changed the strict `<` comparison to `<=`, introducing the vulnerability. Version 0.1.0-rc.4 fixes the issue.

Products
Not specified
Affected versions
Not specified
Fixed versions
Not specified
CVEs
CVE-2026-24850
Confirmed fixed CVEs
Not specified
Updated in this feed
4 Nov 2026, 18:28 UTC · Revision 1

Source evidence

ML-DSA Signature Verification Accepts Signatures with Repeated Hint Indices

core-osv · Original source

Published 28 Jan 2026, 00:24 UTC

The ML-DSA crate is a Rust implementation of the Module-Lattice-Based Digital Signature Standard (ML-DSA). Starting in version 0.0.4 and prior to version 0.1.0-rc.4, the ML-DSA signature verification implementation in the RustCrypto `ml-dsa` crate incorrectly accepts signatures with repeated (duplicate) hint indices. According to the ML-DSA specification (FIPS 204 / RFC 9881), hint indices within each polynomial must be **strictly increasing**. The current implementation uses a non-strict monotonic check (`<=` instead of `<`), allowing duplicate indices. This is a regression bug. The original implementation was correct, but a commit in version 0.0.4 inadvertently changed the strict `<` comparison to `<=`, introducing the vulnerability. Version 0.1.0-rc.4 fixes the issue.

osv:CVE-2026-24850
Complete source record
{
  "id": "1d4131cd36db6070cf9730a70ea7b6eb12c1c625bd9bcafa796ff5b8f98c50cd",
  "url": "https://osv.dev/vulnerability/CVE-2026-24850",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "ML-DSA Signature Verification Accepts Signatures with Repeated Hint Indices",
    "summary": "The ML-DSA crate is a Rust implementation of the Module-Lattice-Based Digital Signature Standard (ML-DSA). Starting in version 0.0.4 and prior to version 0.1.0-rc.4, the ML-DSA signature verification implementation in the RustCrypto `ml-dsa` crate incorrectly accepts signatures with repeated (duplicate) hint indices. According to the ML-DSA specification (FIPS 204 / RFC 9881), hint indices within each polynomial must be **strictly increasing**. The current implementation uses a non-strict monotonic check (`<=` instead of `<`), allowing duplicate indices. This is a regression bug. The original implementation was correct, but a commit in version 0.0.4 inadvertently changed the strict `<` comparison to `<=`, introducing the vulnerability. Version 0.1.0-rc.4 fixes the issue.",
    "evidence": "osv:CVE-2026-24850",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-24850",
      "aliases": [
        "CVE-2026-24850",
        "GHSA-5x2r-hc65-25f9"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/rustcrypto/signatures",
              "type": "GIT",
              "events": [
                {
                  "introduced": "ea7a000fa4ddac2ddc3eedca2666ac1959736712"
                },
                {
                  "fixed": "f5901031ac84167a28c8d5c47773e13298b417b9"
                },
                {
                  "fixed": "400961412be2e2ab787942cf30e0a9b66b37a54a"
                },
                {
                  "fixed": "b01c3b73dd08d0094e089aa234f78b6089ec1f38"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0.0.4"
                      },
                      {
                        "fixed": "0.1.0-rc.4"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "fixed": "400961412be2e2ab787942cf30e0a9b66b37a54a"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "b01c3b73dd08d0094e089aa234f78b6089ec1f38"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  }
                ]
              }
            }
          ],
          "versions": [
            "dsa/v0.7.0-rc.11",
            "ecdsa/v0.17.0-rc.14",
            "dsa-v0.7.0-rc.10",
            "ecdsa/v0.17.0-rc.13",
            "dsa/v0.7.0-rc.9",
            "ml-dsa/v0.1.0-rc.3",
            "ecdsa/v0.17.0-rc.12",
            "slh-dsa/v0.2.0-rc.2",
            "ecdsa/v0.17.0-rc.11",
            "dsa/v0.7.0-rc.8",
            "ecdsa/v0.17.0-rc.10",
            "ecdsa/v0.17.0-rc.9",
            "slh-dsa/v0.2.0-rc.1",
            "dsa/v0.7.0-rc.7",
            "ml-dsa/v0.1.0-rc.2",
            "ed448/v0.5.0-rc.2",
            "ed25519/v3.0.0-rc.2",
            "rfc6979/v0.5.0-rc.3",
            "ml-dsa/v0.1.0-rc.1",
            "rfc6979/v0.5.0-rc.2",
            "ecdsa/v0.17.0-rc.8",
            "slh-dsa/v0.2.0-rc.0",
            "ml-dsa/v0.1.0-rc.0",
            "lms-signature/v0.1.0-rc.0",
            "ed448/v0.5.0-rc.1",
            "ed25519/v3.0.0-rc.1",
            "ecdsa/v0.17.0-rc.7",
            "dsa/v0.7.0-rc.6",
            "ed448/0.5.0-rc.0",
            "ed25519/v3.0.0-rc.0",
            "rfc6979/v0.5.0-rc.1",
            "ecdsa/v0.17.0-rc.6",
            "dsa/v0.7.0-rc.5",
            "dsa/v0.7.0-rc.4",
            "ecdsa/v0.17.0-rc.5",
            "dsa/v0.7.0-rc.3",
            "ecdsa/v0.17.0-rc.4",
            "dsa/v0.7.0-rc.2",
            "dsa/v0.7.0-rc.1",
            "ecdsa/v0.17.0-rc.3",
            "ecdsa/v0.17.0-rc.2",
            "ecdsa/v0.17.0-rc.1",
            "ed25519/v3.0.0-pre.0",
            "dsa/v0.7.0-rc.0",
            "ecdsa/v0.17.0-rc.0",
            "rfc6979/v0.5.0-rc.0",
            "slh-dsa/v0.0.3",
            "ml-dsa/v0.0.4"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-24850.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:38.524626465Z",
      "provider": "osv",
      "references": [
        "https://csrc.nist.gov/pubs/fips/204/final",
        "https://datatracker.ietf.org/doc/html/rfc9881",
        "https://github.com/C2SP/wycheproof/blob/master/testvectors_v1/mldsa_44_verify_test.json",
        "https://github.com/C2SP/wycheproof/blob/master/testvectors_v1/mldsa_65_verify_test.json",
        "https://github.com/C2SP/wycheproof/blob/master/testvectors_v1/mldsa_87_verify_test.json",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/24xxx/CVE-2026-24850.json",
        "https://github.com/RustCrypto/signatures/security/advisories/GHSA-5x2r-hc65-25f9",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-24850",
        "https://github.com/RustCrypto/signatures/issues/894",
        "https://github.com/RustCrypto/signatures/commit/400961412be2e2ab787942cf30e0a9b66b37a54a",
        "https://github.com/RustCrypto/signatures/commit/b01c3b73dd08d0094e089aa234f78b6089ec1f38",
        "https://github.com/RustCrypto/signatures/pull/895",
        "https://github.com/C2SP/wycheproof"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-347"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/24xxx/CVE-2026-24850.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-24850",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 505697,
  "published_at": "2026-01-28T00:24:53.146+00:00"
}