CVE-2025-48994 — SignXML's signature verification with HMAC is vulnerable to an algorithm confusion attack

Affected: XML-Security signxml

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.

GHSA-6vx8-pcwv-xhf4 — SignXML's signature verification with HMAC is vulnerable to an algorithm confusion attack

Affected: PyPI: signxml

When verifying signatures with X509 certificate validation turned off and HMAC shared secret set (`signxml.XMLVerifier.verify(require_x509=False, hmac_key=...`), prior versions of SignXML 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.

Most recent entries from all

CVE-2025-48994 — SignXML's signature verification with HMAC is vulnerable to an algorithm confusion attack

GHSA-6vx8-pcwv-xhf4 — SignXML's signature verification with HMAC is vulnerable to an algorithm confusion attack