ghsa-6vx8-pcwv-xhf4
Vulnerability from github
Published
2025-06-05 00:38
Modified
2025-06-05 00:38
Severity ?
6.9 (Medium) - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
Summary
SignXML's signature verification with HMAC is vulnerable to an algorithm confusion attack
Details

When verifying signatures with X509 certificate validation turned off and HMAC shared secret set (signxml.XMLVerifier.verify(require_x509=False, hmac_key=...), prior versions of SignXML are vulnerable to a potential algorithm confusion attack. Unless the user explicitly limits the expected signature algorithms using the signxml.XMLVerifier.verify(expect_config=...) setting, an attacker may supply a signature unexpectedly signed with a key other than the provided HMAC key, using a different (asymmetric key) signature algorithm.

Starting with signxml 4.0.4, specifying hmac_key causes the set of accepted signature algorithms to be restricted to HMAC only, if not already restricted by the user.

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{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "signxml"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "4.0.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2025-48994"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-303"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2025-06-05T00:38:20Z",
    "nvd_published_at": "2025-06-02T17:15:40Z",
    "severity": "MODERATE"
  },
  "details": "When verifying signatures with X509 certificate validation turned off and HMAC shared secret set (`signxml.XMLVerifier.verify(require_x509=False, hmac_key=...`), prior versions of SignXML are vulnerable to a potential algorithm confusion attack. Unless the user explicitly limits the expected signature algorithms using the `signxml.XMLVerifier.verify(expect_config=...)` setting, an attacker may supply a signature unexpectedly signed with a key other than the provided HMAC key, using a different (asymmetric key) signature algorithm.\n\nStarting with signxml 4.0.4, specifying `hmac_key` causes the set of accepted signature algorithms to be restricted to HMAC only, if not already restricted by the user.",
  "id": "GHSA-6vx8-pcwv-xhf4",
  "modified": "2025-06-05T00:38:20Z",
  "published": "2025-06-05T00:38:20Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/XML-Security/signxml/security/advisories/GHSA-6vx8-pcwv-xhf4"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-48994"
    },
    {
      "type": "WEB",
      "url": "https://github.com/XML-Security/signxml/commit/e3c0c2b82a3329a65d917830657649c98b8c7600"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/XML-Security/signxml"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "SignXML\u0027s signature verification with HMAC is vulnerable to an algorithm confusion attack"
}


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