VulnerabilityPublished 3 Aug 2026

CVE-2026-9390: TIMLEGGE XML::Sig · XPath Injection

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: 0.5% chance of exploitation in 30 days – higher than 43% 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-mhmm-7px6-jx3j

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 untrusted XML documents with vulnerable versions of XML::Sig. Consider applying input validation or escaping on the SignedInfo/Reference/@URI values before they are used in XPath expressions to mitigate injection risks.

Description

XML::Sig versions before 0.71 for Perl are vulnerable to XPath injection due to improper neutralization of data within XPath expressions. The vulnerability arises because the verify() and _get_signed_xml() functions build XPath queries by concatenating unescaped URI values from the document, allowing an attacker to inject arbitrary XPath operators. This can cause the digest verification process to select unintended XML nodes, potentially compromising the integrity verification of signed XML documents.

Impact

Successful exploitation allows an attacker to manipulate the XPath query used during XML signature verification, causing the verification process to validate unintended XML nodes. This can lead to bypassing signature integrity checks, potentially allowing tampering with signed XML data without detection. The CVSS score of 9.1 indicates a critical severity with high confidentiality and integrity impact, no privileges required, and no user interaction needed.

Summary

CVE-2026-9390 describes an XPath injection vulnerability in XML::Sig for Perl versions prior to 0.71. The functions verify() and _get_signed_xml() construct XPath expressions by directly concatenating the SignedInfo/Reference/@URI value from the XML document without escaping or validating it against the NCName grammar. An attacker can craft a URI containing a single quote to break out of the string literal in the XPath expression and append arbitrary XPath operators. This manipulation can cause the XPath query to match XML elements not intended by the reference, potentially allowing an attacker to influence which node is selected for digest verification and thus undermine the signature validation process.

CWE-643Improper Neutralization of Data within XPath Expressions (XPath Injection) (opens in a new tab)
Base weaknessLikelihood of exploit: HighOWASP Top 10 A05:2025: Injection (opens in a new tab)
The product uses external input to dynamically construct an XPath expression used to retrieve data from an XML database, but it does not neutralize or incorrectly neutralizes that input.
Implementation
Use parameterized XPath queries (e.g. using XQuery). This will help ensure separation between data plane and control plane.
Implementation
Properly validate user input. Reject data where appropriate, filter where appropriate and escape where appropriate. Make sure input that will be used in XPath queries is safe in that context.
OWASP Cheat Sheets
XML Security (opens in a new tab)
XML External Entity Prevention (opens in a new tab)
Injection Prevention (opens in a new tab)
Injection Prevention in Java (opens in a new tab)
Abuse Case (opens in a new tab)
OWASP ASVS 4.0.3
V5.3.10 (opens in a new tab)
V1.5.1 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-1287Improper Validation of Specified Type of Input (opens in a new tab)
Base weakness
The product receives input that is expected to be of a certain type, but it does not validate or incorrectly validates that the input is actually of the expected type.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (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, 14:58 UTC

WeaknessesCWE-643, CWE-1287

Technical details

References

Community reviews

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