VulnerabilityPublished 3 Aug 2026

CVE-2026-9487: TIMLEGGE XML::Sig · Improper Verification of Cryptographic Signature

Affects TIMLEGGE XML::SigSource CVE Database V5

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Not known to be exploited · CVSS 9.1 Critical : upgrade to 0.71 as a priority.

Data as of 1 Nov 2026, 22:58 UTC

CVSS 3.1 base score

9.1Critical

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.2% chance of exploitation in 30 days – higher than 20% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 0.71

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: High
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 3 Aug 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 1 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

ghsa-wqp7-2ww4-q6mf

What to do

Upgrade XML::Sig and XML-Sig to 0.71.

Affected software

Product	Affected	Fixed in
TIMLEGGEXML::Sig	Affected <0.71	Fixed in 0.71
GitHubXML-Sig`pkg:github/XML-Sig`Other threats	Affected <0.71	Fixed in 0.71

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

If you cannot patch yet, users should avoid processing XML documents with duplicate ID attributes or implement additional checks to detect and reject documents containing duplicate IDs during signature verification.

Description

XML::Sig versions before 0.71 for Perl contain a critical vulnerability that allows signature wrapping via duplicate ID values. The _get_signed_xml() function resolves SignedInfo Reference/@URI by selecting the first node with a matching ID, but does not detect if multiple elements share that ID. This can cause a document with duplicate IDs to verify successfully while an attacker controls the second element, potentially compromising SAML2 assertions.

Impact

An attacker can exploit this vulnerability to bypass signature verification by using duplicate ID values in XML documents, enabling signature wrapping attacks. This can lead to unauthorized manipulation of signed data, such as SAML2 assertions, potentially allowing attackers to impersonate users or escalate privileges. The vulnerability affects confidentiality and integrity but does not impact availability.

Summary

CVE-2026-9487 is a critical vulnerability in XML::Sig versions prior to 0.71 where improper verification of cryptographic signatures occurs due to duplicate ID values in XML documents. The function _get_signed_xml() uses an XPath expression to select the first node matching a given ID but does not detect duplicates. This allows an attacker to craft a document with two elements sharing the same ID, where the signature verification checks the first element but an application may process the second, attacker-controlled element. In SAML2 contexts, this can lead to assertion manipulation under attacker control. The vulnerability is classified as CWE-347 (Improper Verification of Cryptographic Signature) and has a CVSS 3.1 base score of 9.1 (critical).

CWE-347Improper Verification of Cryptographic Signature (opens in a new tab)
Base weaknessOWASP Top 10 A04:2025: Cryptographic Failures (opens in a new tab)
The product does not verify, or incorrectly verifies, the cryptographic signature for data.
OWASP Cheat Sheets
XML Security (opens in a new tab)
REST Security (opens in a new tab)
JSON Web Token for Java (opens in a new tab)
REST Assessment (opens in a new tab)
Cross-Site Request Forgery Prevention (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.2 (opens in a new tab)
V3.5.3 (opens in a new tab)
V13.2.6 (opens in a new tab)
Attack patterns
Padding Oracle Crypto Attack (opens in a new tab)
Signature Spoofing by Improper Validation (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 10 Aug 2026, 14:59 UTC

WeaknessesCWE-347

Technical details

References

Community reviews

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