ghsa-c4cc-x928-vjw9
Vulnerability from github
Published
2025-12-08 17:57
Modified
2025-12-09 19:17
Severity ?
6.0 (Medium) - CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:L/A:L
Summary
robrichards/xmlseclibs has an Libxml2 Canonicalization error which can bypass Digest/Signature validation
Details

Summary

An authentication bypass vulnerability exists due to a flaw in the libxml2 canonicalization process, which is used by xmlseclibs during document transformation. This weakness allows an attacker to generate a valid signature once and reuse it indefinitely. In practice, a signature created during a previous interaction - or through a misconfigured authentication flow - can be replayed to bypass authentication checks.

Details

When libxml2’s canonicalization is invoked on an invalid XML input, it may return an empty string rather than a canonicalized node. xmlseclibs then proceeds to compute the DigestValue over this empty string, treating it as if canonicalization succeeded.

https://github.com/robrichards/xmlseclibs/blob/f4131320c6dcd460f1b0c67f16f8bf24ce4b5c3e/src/XMLSecurityDSig.php#L296

Impact

Digest bypass: By crafting input that causes canonicalization to yield an empty string, the attacker can manipulate validation to pass incorrectly.

Signature replay on empty canonical form: If an empty string has been signed once (e.g., in a prior interaction or via a misconfigured flow), that signature can potentially be replayed to bypass authentication.

Suggested remediation

Treat canonicalization failures (exceptions or nil/empty outputs) as fatal and abort validation. Add explicit checks: reject when canonicalize returns nil/empty or raise

Show details on source website

To clipboard 

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 3.1.3"
      },
      "package": {
        "ecosystem": "Packagist",
        "name": "robrichards/xmlseclibs"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.1.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2025-66578"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-248"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2025-12-08T17:57:33Z",
    "nvd_published_at": "2025-12-09T16:18:21Z",
    "severity": "MODERATE"
  },
  "details": "### Summary\nAn authentication bypass vulnerability exists due to a flaw in the libxml2 canonicalization process, which is used by [xmlseclibs](https://github.com/robrichards/xmlseclibs) during document transformation. This weakness allows an attacker to generate a valid signature once and reuse it indefinitely. In practice, a signature created during a previous interaction - or through a misconfigured authentication flow - can be replayed to bypass authentication checks.\n\n### Details\nWhen libxml2\u2019s canonicalization is invoked on an invalid XML input, it may return an empty string rather than a canonicalized node. [xmlseclibs](https://github.com/robrichards/xmlseclibs) then proceeds to compute the DigestValue over this empty string, treating it as if canonicalization succeeded.\n\nhttps://github.com/robrichards/xmlseclibs/blob/f4131320c6dcd460f1b0c67f16f8bf24ce4b5c3e/src/XMLSecurityDSig.php#L296\n\n### Impact\nDigest bypass: By crafting input that causes canonicalization to yield an empty string, the attacker can manipulate validation to pass incorrectly.\n\nSignature replay on empty canonical form: If an empty string has been signed once (e.g., in a prior interaction or via a misconfigured flow), that signature can potentially be replayed to bypass authentication.\n\n### Suggested remediation\nTreat canonicalization failures (exceptions or nil/empty outputs) as fatal and abort validation.\nAdd explicit checks: reject when canonicalize returns nil/empty or raise",
  "id": "GHSA-c4cc-x928-vjw9",
  "modified": "2025-12-09T19:17:52Z",
  "published": "2025-12-08T17:57:33Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/robrichards/xmlseclibs/security/advisories/GHSA-c4cc-x928-vjw9"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-66578"
    },
    {
      "type": "WEB",
      "url": "https://github.com/robrichards/xmlseclibs/commit/69fd63080bc47a8d51bc101c30b7cb756862d1d6"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/robrichards/xmlseclibs"
    },
    {
      "type": "WEB",
      "url": "https://github.com/robrichards/xmlseclibs/blob/f4131320c6dcd460f1b0c67f16f8bf24ce4b5c3e/src/XMLSecurityDSig.php#L296"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:L/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "robrichards/xmlseclibs has an Libxml2 Canonicalization error which can bypass Digest/Signature validation"
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
  • Confirmed: The vulnerability is confirmed from an analyst perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
  • Patched: This vulnerability was successfully patched by the user reporting the sighting.
  • Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
  • Not confirmed: The user expresses doubt about the veracity of the vulnerability.
  • Not patched: This vulnerability was not successfully patched by the user reporting the sighting.