XML::Sig versions before 0.71 for Perl allow signature wrapping via duplicate ID.
_get_signed_xml() in lib/XML/Sig.pm, called from verify(), resolves the SignedInfo Reference/@URI to a node with the XPath expression "//*[@ID='$id']" and returns the first node of the resulting node set. A document in which two elements share that ID value is accepted: the digest and signature are checked against whichever element comes first in document order, and the duplicate is not detected.
Such a document verifies successfully while an application that resolves the same ID independently can read the second, attacker supplied element; in a SAML2 context this places the contents of an Assertion under attacker control.
CVSS Details
- CVSS 3.1 Base Score: 9.1
- CVSS 3.1 Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N)
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