{"id":"CVE-2025-48995","aliases":["GHSA-gmhf-gg8w-jw42","PYSEC-2026-1922"],"url":"https://o3.security/vulnerability/CVE-2025-48995","summary":"SignXML's signature verification with HMAC is vulnerable to a timing attack","details":"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.","published":"2025-06-02T16:23:27.706Z","modified":"2026-08-12T03:51:25.251278703Z","cvss":null,"epss":{"score":0.00212,"percentile":0.113,"asOf":"2026-08-24"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"signxml","fixedVersion":"4.0.4"}],"fix":{"url":"https://github.com/XML-Security/signxml/commit/1b501faaacf34cf978a52dbc6915ec11e27611cd","label":"XML-Security/signxml@1b501fa"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/48xxx/CVE-2025-48995.json"},{"type":"ADVISORY","url":"https://github.com/XML-Security/signxml/security/advisories/GHSA-gmhf-gg8w-jw42"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-48995"},{"type":"FIX","url":"https://github.com/XML-Security/signxml/commit/1b501faaacf34cf978a52dbc6915ec11e27611cd"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:25.251278703Z"}}