EUVD-2026-52325
GHSA-r3hj-rg3j-262c
Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Network-reachable with no prerequisites beyond submitting XML; full integrity bypass with no confidentiality or availability impact, consistent with NVD scoring.
Primary rating from Vendor (CPANSec).
CVSS VectorVendor: CPANSec
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Lifecycle Timeline
5DescriptionCVE.org
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.
verify 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.
Any 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.
AnalysisAI
Signature verification bypass in XML::Sig (Perl) versions 0.29 through 0.71 allows remote unauthenticated attackers to submit arbitrary XML documents that are accepted as cryptographically valid without any digest or key check ever running. The verify() function unconditionally returns true after looping over all dsig:Signature elements, even when every iteration exited early via a skip path before cryptographic validation. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires the target application to pass attacker-controlled XML to XML::Sig's verify() function on a version between 0.29 and 0.71 inclusive. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 3.1 score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N) accurately represents the attack profile: no authentication required, no user interaction, low complexity, and full integrity bypass. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker submits a crafted XML document to a SAML assertion processor or other XML signature-verifying application built on XML::Sig 0.29-0.71. The document contains two dsig:Signature elements whose SignedInfo/Reference/@URI values reference an element ID that does not exist anywhere in the document. … |
| Remediation | Upgrade XML::Sig to version 0.72 or later using 'cpanm XML::Sig' or the equivalent package manager command; the release is confirmed at https://metacpan.org/release/TIMLEGGE/XML-Sig-0.72/changes and the source patch at https://github.com/perl-net-saml2/perl-XML-Sig/commit/ef22cfed1ac0f29b316d17eb79cf6480e03ae16a.patch. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, identify all systems using XML::Sig (Perl) through dependency scans and code inventory, and verify which versions are deployed. …
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External POC / Exploit Code
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