PT-2026-67420 · Timlegge · Xml::Sig

CVE-2026-9390 · Published 2026-08-03 · Updated 2026-08-03

NVD

CVSS v3.1

9.1

Critical

Base vector

AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

XML::Sig versions before 0.71 for Perl allow XPath injection in ID lookup.

verify() and get signed xml() in lib/XML/Sig.pm build XPath expressions by concatenating the SignedInfo/Reference/@URI value read from the document being verified. The value is neither escaped nor checked against the NCName grammar that XML requires of an ID, so a URI containing a single quote closes the string literal in the generated expression and appends arbitrary XPath operators.

A crafted URI can make the lookup match elements the reference does not name, or every element in the document, so which node is selected for digest verification is decided by the injected expression rather than by the reference.

Fix

Weakness Enumeration

CWE-1287

CWE-643

Related Identifiers

CVE-2026-9390

Affected Products

Xml::Sig

References · 4

• https://github.com/perl-net-saml2/perl-XML-Sig/commit/69ad2b421118fadd33d57f50b110b8d161e8fef5.patch · Patch
• https://github.com/perl-net-saml2/perl-XML-Sig/commit/a85aad21aa767ac1c158bbfc19447683941ab376.patch · Patch
• https://nvd.nist.gov/vuln/detail/CVE-2026-9390 · Security Note
• https://metacpan.org/release/TIMLEGGE/XML-Sig-0.71/changes · Note