python-signxml — security advisory

{
  "id": "b36f3bc5a42cfaaa511fe2cafd66b0df1d197f9e09362d4745b09e6ed9d3a361",
  "url": "https://osv.dev/vulnerability/UBUNTU-CVE-2025-48995",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "UBUNTU-CVE-2025-48995",
    "summary": "SignXML is an implementation of the W3C XML Signature standard in Python. When verifying signatures with X509 certificate validation turned off and HMAC shared secret set (`signxml.XMLVerifier.verify(require_x509=False, hmac_key=...`), versions of SignXML prior to 4.0.4 are vulnerable to a potential timing attack. The verifier may leak information about the correct HMAC when comparing it with the user supplied hash, allowing users to reconstruct the correct HMAC for any data.",
    "evidence": "osv:UBUNTU-CVE-2025-48995",
    "products": [
      {
        "name": {
          "value": "python-signxml",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "4.0.3+dfsg-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "4.0.5+dfsg-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "4.0.5+dfsg-2",
            "evidence": "/affected/0/versions"
          }
        ]
      },
      {
        "name": {
          "value": "python-signxml",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "4.2.0+dfsg-1",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "4.4.0+dfsg-1",
            "evidence": "/affected/1/versions"
          }
        ]
      },
      {
        "name": {
          "value": "python-signxml",
          "evidence": "/affected/2/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "4.0.5+dfsg-2",
            "evidence": "/affected/2/versions"
          },
          {
            "value": "4.2.0+dfsg-1",
            "evidence": "/affected/2/versions"
          }
        ]
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "UBUNTU-CVE-2025-48995",
      "aliases": [
        "UBUNTU-CVE-2025-48995"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N"
        },
        {
          "type": "Ubuntu",
          "score": "medium"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "python-signxml",
            "purl": "pkg:deb/ubuntu/python-signxml?arch=source&distro=questing",
            "ecosystem": "Ubuntu:25.10"
          },
          "versions": [
            "4.0.3+dfsg-1",
            "4.0.5+dfsg-1",
            "4.0.5+dfsg-2"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-48995.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "python3-signxml",
                "binary_version": "4.0.5+dfsg-2"
              }
            ]
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "python-signxml",
            "purl": "pkg:deb/ubuntu/python-signxml?arch=source&distro=stonking",
            "ecosystem": "Ubuntu:26.10"
          },
          "versions": [
            "4.2.0+dfsg-1",
            "4.4.0+dfsg-1"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-48995.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "python3-signxml",
                "binary_version": "4.4.0+dfsg-1"
              }
            ]
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "python-signxml",
            "purl": "pkg:deb/ubuntu/python-signxml?arch=source&distro=resolute",
            "ecosystem": "Ubuntu:26.04:LTS"
          },
          "versions": [
            "4.0.5+dfsg-2",
            "4.2.0+dfsg-1"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-48995.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "python3-signxml",
                "binary_version": "4.2.0+dfsg-1"
              }
            ]
          }
        }
      ],
      "modified": "2026-10-17T12:57:06.186463526Z",
      "provider": "osv",
      "upstream": [
        "CVE-2025-48995"
      ],
      "references": [
        "https://ubuntu.com/security/CVE-2025-48995",
        "https://www.cve.org/CVERecord?id=CVE-2025-48995",
        "https://github.com/XML-Security/signxml/security/advisories/GHSA-gmhf-gg8w-jw42",
        "https://github.com/XML-Security/signxml/commit/1b501faaacf34cf978a52dbc6915ec11e27611cd"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2025-48995",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 356721,
  "published_at": "2025-06-02T17:15:00+00:00"
}