CVSS 4.0
6.9 mediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:NCVE-2025-48995
Medium (6.9). EPSS 0.2% chance of exploitation in the next 30 days. Fixed in signxml 4.0.4.
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.
Severity
- EPSS
- 0.2% chance of exploitation in the next 30 days; higher than 15% of CVEs (scores of 2026-10-31)
- CWE
- CWE-208
- Published
- Modified
- Record from
- the NVD, synced
Packages (OSV)
| Advisory | Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|---|
| GHSA-gmhf-gg8w-jw42 | PyPI | signxml | <4.0.4 | 4.0.4 |
| PYSEC-2026-1922 | PyPI | signxml | <4.0.4 | 4.0.4 |