CVE-2025-40934VulnerabilityPublished 26 Nov 2025Updated 28 Nov 2025

CVE-2025-40934: TIMLEGGE XML::Sig · Improper Verification of Cryptographic Signature

Affects TIMLEGGE XML::SigSource CVE Database V5

Not known to be exploited · CVSS 9.3 Critical.

Data as of 26 Oct 2026, 06:26 UTC

CVSS 3.1 base score

9.3Critical

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

EPSS: 0.1% chance of exploitation in 30 days – higher than 5% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Changed
Confidentiality: Low
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: Changed: An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.
Confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
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 26 Nov 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: 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 2026-10-26.

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.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC 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.

What to do

Affected software

Product	Affected	Fixed in
TIMLEGGE XML::Sig	Affected =0.27	Fixed in–

AI-suggested

1. Immediately audit all systems and applications using the TIMLEGGE XML::Sig Perl module, identifying versions between 0.27 and 0.67. 2. Where possible, disable or replace XML::Sig usage with alternative, verified XML signature validation libraries that correctly enforce signature presence and validation. 3. Implement additional application-layer checks to verify the presence and validity of XML signatures before processing or accepting XML documents. 4. Employ strict input validation and XML schema validation to detect and reject unsigned or malformed XML documents. 5. Monitor network traffic and application logs for anomalous XML documents lacking signatures or exhibiting suspicious patterns. 6. Prepare to apply vendor patches or updates as soon as they become available, and subscribe to vendor security advisories. 7. Consider deploying Web Application Firewalls (WAFs) with custom rules to detect and block unsigned XML payloads. 8. Educate developers and system administrators about the risks of improper signature validation and encourage secure coding practices around XML processing.

Description

XML-Sig versions 0.27 through 0.67 for Perl incorrectly validates XML files if signatures are omitted. An attacker can remove the signature from the XML document to make it pass the verification check. XML-Sig is a Perl module to validate signatures on XML files. An unsigned XML file should return an error message. The affected versions return true when attempting to validate an XML file that contains no signatures.

Impact

For European organizations, especially those in sectors that rely heavily on XML for secure data exchange—such as finance, government, healthcare, and critical infrastructure—this vulnerability poses a severe risk. Attackers can exploit this flaw to bypass signature verification, potentially injecting malicious XML payloads that could alter transactions, manipulate configurations, or escalate privileges within applications. This undermines trust in digital signatures and can lead to data integrity breaches, unauthorized access, and operational disruptions. Given the widespread use of Perl in legacy systems and backend processes in Europe, organizations may have unpatched systems vulnerable to this attack. The critical severity and network exploitability mean attackers can remotely compromise systems without authentication, increasing the likelihood of targeted attacks or automated exploitation campaigns. The lack of a patch at the time of disclosure further elevates the risk, necessitating immediate compensating controls to prevent exploitation.

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

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 3 Dec 2025, 23:45 UTC

WeaknessesCWE-347

Technical details

References

Community reviews

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