medium6.9
CVE-2025-48995
SignXML's signature verification with HMAC is vulnerable to a timing attack
Impact
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 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.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| pip | signxml | < 4.0.4 | 4.0.4 |
Affected products
| Product | Affected versions |
|---|---|
| SignXML | before 4.0.4 |
Versions were read from the advisory text. No structured product data has been published for this record yet.
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/XML-Security/signxml/commit/1b501faaacf34cf978a52dbc6915ec11e27611cd
- https://github.com/XML-Security/signxml/security/advisories/GHSA-gmhf-gg8w-jw42
- https://github.com/advisories/GHSA-gmhf-gg8w-jw42
- https://nvd.nist.gov/vuln/detail/CVE-2025-48995