GHSA-6vx8-pcwv-xhf4
SignXML's signature verification with HMAC is vulnerable to an algorithm confusion attack
Packages
Details
As written in the advisory (Markdown source, shown as plain text).
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.
References
External links from the advisory. They lead to third-party sites.