SEPTEMBER 17, 2026
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Case File

CVE-2026-18568

HIGH · CVSS 7.5 EPSS 0.19% Public Exploit

Source: NVD + CISA KEV + EPSS · Published 2026-08-03 · Last synced 2026-09-02

CyberRota Analysis

AI-Generated

The vulnerability exists in XML::Sig versions prior to 0.72 for Perl, where the signature verification process can be bypassed, allowing untrusted XML documents to be incorrectly validated as legitimate. This flaw occurs when the verification function returns true without performing any cryptographic checks, potentially leading to unauthorized access or data manipulation. Organizations using affected versions should prioritize patching this vulnerability to mitigate risks associated with processing untrusted XML inputs.

Public Exploit Signal

A public exploit, PoC, GitHub repository or Metasploit reference was detected for this CVE.

GitHub PoC Links

Note: these links are listed for security research and verification purposes only.

CVE
CVE-2026-18568
Severity
HIGH
CVSS
7.5
EPSS
0.19%

Original NVD Description

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.

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