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CVE-2026-18568— 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

Quick assessment

Affected
TIMLEGGE XML::Sig
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

timlegge XML::Sig是timlegge个人开发者的一款处理XML数字签名的Perl模块。 timlegge XML::Sig 0.29版本至0.72之前版本存在加密问题漏洞，该漏洞源于签名验证逻辑不完善，在lib/XML/Sig.pm中的verify函数中，当所有签名在摘要或密钥检查前被跳过时，无条件返回1，可能导致攻击者绕过签名验证。

AI Predicted 9.1 Difficulty: Easy EPSS 0.32% · P22

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 1

VendorProduct Version RangeStatus
TIMLEGGE XML::Sig 0.29< 0.72 affected
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I. Basic Information for CVE-2026-18568

Vulnerability Information
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Vulnerability Title
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
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
密码学签名的验证不恰当
Source: CVE Program / CVE List V5
Vulnerability Title
timlegge XML::Sig 加密问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
timlegge XML::Sig是timlegge个人开发者的一款处理XML数字签名的Perl模块。 timlegge XML::Sig 0.29版本至0.72之前版本存在加密问题漏洞，该漏洞源于签名验证逻辑不完善，在lib/XML/Sig.pm中的verify函数中，当所有签名在摘要或密钥检查前被跳过时，无条件返回1，可能导致攻击者绕过签名验证。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
TIMLEGGE XML::Sig 0.29 ~ 0.72 -

II. Public POCs for CVE-2026-18568

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III. Intelligence Information for CVE-2026-18568

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Patches & Fixes for CVE-2026-18568 (1)

Vendor Pages for CVE-2026-18568 (1)

Other References for CVE-2026-18568 (1)

Same Patch Batch · TIMLEGGE · 2026-08-03 · 6 CVEs total

CVE-2026-18108 Net::SAML2 versions before 0.86 for Perl allow authentication bypass because _verify_encry
CVE-2026-18092 Net::SAML2 versions before 0.86 for Perl allow SAML authentication bypass via XML signatur
CVE-2026-18089 Net::SAML2 versions before 0.86 for Perl allow SAML authentication bypass by verifying res
CVE-2026-9390 XML::Sig versions before 0.71 for Perl allow XPath injection in ID lookup
CVE-2026-9487 XML::Sig versions before 0.71 for Perl allow signature wrapping via duplicate ID

IV. Related Vulnerabilities

Same product: XML::Sig
Same vendor: TIMLEGGE
Same weakness: CWE-347

V. Comments for CVE-2026-18568

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