CVE-2025-48994
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 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.
- Score
- CVSS 4.0 6.9 Medium
- Status
- Deferred - security-advisories@github.com
- Published
- 2025-06-02
- Last modified
- 2025-06-02
- Weaknesses
- CWE-303
Affected products
References
- https://github.com/XML-Security/signxml/commit/e3c0c2b82a3329a65d917830657649c98b8c7600
- https://github.com/XML-Security/signxml/security/advisories/GHSA-6vx8-pcwv-xhf4
