CVE-2025-48995
SignXML's signature verification with HMAC is vulnerable to a timing attack
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SignXML's signature verification with HMAC is vulnerable to a timing 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 timing attack. The verifier may leak information about the correct HMAC when comparing it with the user supplied hash, allowing users to reconstruct the correct HMAC for any data.
Reserved 2025-05-29 | Published 2025-06-02 | Updated 2025-06-02 | Assigner GitHub_MCWE-208: Observable Timing Discrepancy
github.com/...ignxml/security/advisories/GHSA-gmhf-gg8w-jw42
github.com/...ommit/1b501faaacf34cf978a52dbc6915ec11e27611cd
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