robrichards/xmlseclibs has an Libxml2 Canonicalization error which can bypass Digest/Signature validation
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.
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
Software afectado
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| Plataforma | Paquete | Versiones vulnerables | Corregida en |
|---|---|---|---|
| Paquete de Composer | robrichards/xmlseclibs | < 3.1.4 | 3.1.4 |
Referencias
- https://github.com/robrichards/xmlseclibs/security/advisories/GHSA-c4cc-x928-vjw9
- https://nvd.nist.gov/vuln/detail/CVE-2025-66578
- https://github.com/robrichards/xmlseclibs/commit/69fd63080bc47a8d51bc101c30b7cb756862d1d6
- https://github.com/robrichards/xmlseclibs
- https://github.com/robrichards/xmlseclibs/blob/f4131320c6dcd460f1b0c67f16f8bf24ce4b5c3e/src/XMLSecurityDSig.php#L296
- Vector CVSS
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:L/A:L- Debilidad (CWE)
CWE-248- Plataforma
- Composer
- Paquete
robrichards/xmlseclibs- Publicada
- 08.12.2025
- Actualizado
- 11.10.2026 10:22
Fuentes y licencias
OSV / GitHub Advisory Database - GHSA-c4cc-x928-vjw9 - CC BY 4.0
Historial de vulnerabilidades: robrichards/xmlseclibs
Todas las vulnerabilidades publicadas de este paquete (Paquete de Composer), de la más reciente a la más antigua. Muestra si es un fallo aislado o un paquete que hay que vigilar.
- Entradas en total
- 4
- Primera → última
- 11.2019 03.2026
- Sin corrección
- 0
- Explotada en ataques
- 0
Distribución por gravedad
- Alta 3
- Media 1
Divulgaciones por año
- 2019: 1
- 2020: 0
- 2021: 0
- 2022: 0
- 2023: 0
- 2024: 1
- 2025: 1
- 2026: 1
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robrichards/xmlseclibs has an Libxml2 Canonicalization error which can bypass Digest/Signature validation esta entrada
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