CVE-2026-9487Public exploitNetwork attack vector

Trusted XML manipulation via duplicate ID resolution

Published Aug 3, 2026 · Updated Aug 3, 2026

Signature verification in Timothy Legge XML::Sig before 0.71 allows remote attackers to control trusted XML content via duplicate IDs. The verify() path calls _get_signed_xml(), whose XPath lookup selects the first element matching Reference/@URI without rejecting a second element with the same ID. A signed-first, attacker-supplied-second document passes verification while an application can consume the unsigned duplicate, placing SAML2 Assertion contents under attacker control.

CVSS severity9.1
Critical
EPSS probability0.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Signature verification in Timothy Legge XML::Sig before 0.71 allows remote attackers to control trusted XML content via duplicate IDs. The verify() path calls _get_signed_xml(), whose XPath lookup selects the first element matching Reference/@URI without rejecting a second element with the same ID. A signed-first, attacker-supplied-second document passes verification while an application can consume the unsigned duplicate, placing SAML2 Assertion contents under attacker control.

The record

CVE
CVE-2026-9487
Published
Aug 3, 2026
Updated
Aug 3, 2026
Vendor
Timothy Legge
Product
XML::Sig
Classifications
CWE-347, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 3, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <0.71

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Timothy Legge · XML::Sigversion=0 <0.71

Published CVSS scores

9.1CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-347Improper Verification of Cryptographic Signature
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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