{"id":"CVE-2026-18568","summary":"XML::Sig versions from 0.29 before 0.72 for Perl allow signature verification bypass because verify returns true when every signature was skipped before any cryptographic check","details":"XML::Sig versions from 0.29 before 0.72 for Perl allow signature verification bypass because verify returns true when every signature was skipped before any cryptographic check.\n\nverify in lib/XML/Sig.pm counts the `//dsig:Signature` elements into `$numsigs` and iterates over them, but two paths reach `next` before any digest or key check runs: a `SignedInfo/Reference/@URI` that resolves to no element while `$numsigs` is greater than 1, and, when `id_attr` is set, a reference that does not match the requested ID. The loop records nothing about what it checked, so when every signature takes one of those paths control reaches the unconditional `return 1` that ends verify. Two `Signature` elements whose Reference URI names an ID that no element carries is enough, as is one such element combined with `id_attr`.\n\nAny caller that passes untrusted XML to verify can receive a true return for a document in which no digest and no signature value was checked; a `cert` or `cert_text` trust anchor does not change this, because no key check runs. Versions up to 0.28 use an XML::XPath based verify that has no such skip and are not affected.","modified":"2026-08-08T03:48:18.677194921Z","published":"2026-08-03T14:38:52.540Z","database_specific":{"cna_assigner":"CPANSec","cwe_ids":["CWE-347"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/18xxx/CVE-2026-18568.json"},"references":[{"type":"WEB","url":"https://cpan.org/modules"},{"type":"WEB","url":"https://www.cve.org/CVERecord?id=CVE-2025-40934"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/18xxx/CVE-2026-18568.json"},{"type":"ADVISORY","url":"https://metacpan.org/release/TIMLEGGE/XML-Sig-0.72/changes"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-18568"},{"type":"FIX","url":"https://github.com/perl-net-saml2/perl-XML-Sig/commit/ef22cfed1ac0f29b316d17eb79cf6480e03ae16a.patch"},{"type":"PACKAGE","url":"https://github.com/perl-net-saml2/perl-XML-Sig"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/perl-net-saml2/perl-xml-sig","events":[{"introduced":"1b1e2fc5257d518c95b77c996a9b45a80f578766"},{"fixed":"fed89d10445c64ad054d9b1820bf3e21d56ddf69"},{"fixed":"ef22cfed1ac0f29b316d17eb79cf6480e03ae16a"}],"database_specific":{"cpe":"cpe:2.3:a:xml\\:\\:sig_project:xml\\:\\:sig:*:*:*:*:*:perl:*:*","extracted_events":[{"introduced":"0.29"},{"fixed":"0.72"}],"source":["CPE_RANGE","REFERENCES"]}}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-18568.json"}}],"schema_version":"1.8.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N"}]}