CVE-2025-48994
SignXML's signature verification with HMAC is vulnerable to an algorithm confusion attack
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SignXML's signature verification with HMAC is vulnerable to an algorithm confusion attack
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.
Reserved 2025-05-29 | Published 2025-06-02 | Updated 2025-06-02 | Assigner GitHub_MCWE-303: Incorrect Implementation of Authentication Algorithm
github.com/...ignxml/security/advisories/GHSA-6vx8-pcwv-xhf4
github.com/...ommit/e3c0c2b82a3329a65d917830657649c98b8c7600
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