CAPEC-84

XQuery Injection

Very High severityHigh likelihoodDetailed pattern

This attack utilizes XQuery to probe and attack server systems; in a similar manner that SQL Injection allows an attacker to exploit SQL calls to RDBMS, XQuery Injection uses improperly validated data that is passed to XQuery commands to traverse and execute commands that the XQuery routines have access to. XQuery injection can be used to enumerate elements on the victim's environment, inject commands to the local host, or execute queries to remote files and data sources.

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How the attack unfolds
Prerequisites
Skills required
Consequences
Mitigations
Weaknesses it exploits
Related attack patterns
Examples

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Explain the attack pattern CAPEC-84: XQuery Injection: how it unfolds, what it needs and how to prevent and detect it in my systems. Use https://capec.mitre.org/data/definitions/84.html and https://cve.bz/cve/capec/84?via=ask-ai-copy, which lists recent CVEs with the weaknesses it exploits. Cite the sources.

Opens a third-party assistant; its answer is its own, not cve.bz's. The prompt holds only this attack pattern's id and public links.

How the attack unfolds

Explore
The attacker looks for a way in.
1. [Survey the application for user-controllable inputs] Using a browser or an automated tool, an attacker follows all public links and actions on a web site. They record all the links, the forms, the resources accessed and all other potential entry-points for the web application.
  3 techniques
  - Use a spidering tool to follow and record all links and analyze the web pages to find entry points. Make special note of any links that include parameters in the URL.
  - Use a proxy tool to record all user input entry points visited during a manual traversal of the web application.
  - Use a browser to manually explore the website and analyze how it is constructed. Many browsers' plugins are available to facilitate the analysis or automate the discovery.
Experiment
They probe what they found.
1. [Determine user-controllable input susceptible to injection] Determine the user-controllable input susceptible to injection. For each user-controllable input that the attacker suspects is vulnerable to XQL injection, attempt to inject characters that have special meaning in XQL. The goal is to create an XQL query with an invalid syntax.
  5 techniques
  - Use web browser to inject input through text fields or through HTTP GET parameters.
  - Use a web application debugging tool such as Tamper Data, TamperIE, WebScarab,etc. to modify HTTP POST parameters, hidden fields, non-freeform fields, etc.
  - Use XML files to inject input.
  - Use network-level packet injection tools such as netcat to inject input
  - Use modified client (modified by reverse engineering) to inject input.
Exploit
They carry out the attack.
1. [Information Disclosure] The attacker crafts and injects an XQuery payload which is acted on by an XQL query leading to inappropriate disclosure of information.
  1 technique
  - Leveraging one of the vulnerable inputs identified during the Experiment phase, inject malicious XQuery payload. The payload aims to get information on the structure of the underlying XML database and/or the content in it.
2. [Manipulate the data in the XML database] The attacker crafts and injects an XQuery payload which is acted on by an XQL query leading to modification of application data.
  1 technique
  - Leveraging one of the vulnerable inputs identified during the Experiment phase, inject malicious XQuery payload.. The payload tries to insert or replace data in the XML database.

Prerequisites

The XQL must execute unvalidated data

Skills required

Low skill
Basic understanding of XQuery

Consequences

What a successful attack can lead to
Impact	Affects	Note
Modify Data	Integrity
Read Data	Confidentiality
Gain Privileges	Confidentiality, Access Control, Authorization
Execute Unauthorized Commands	Confidentiality, Integrity, Availability	Run Arbitrary Code

Mitigations

Design: Perform input allowlist validation on all XML input
Implementation: Run xml parsing and query infrastructure with minimal privileges so that an attacker is limited in their ability to probe other system resources from XQL.

Weaknesses it exploits

CWE-74 Improper Neutralization of Special Elements in Output Used by a Downstream Component
CWE-707 Improper Neutralization

Recent CVEs with these weaknesses

5.3CVE-2026-634972026-11-09
titra is an open source time tracking project. In versions 1.0.3 and prior, authenticated API users can abuse the customfields object to inject or overwrite top-level fields in MongoDB documents. At time of publication, there are no public…
2.1CVE-2026-1249872026-11-09
A vulnerability has been found in mikefarah yq up to 4.53.3. This affects the function Encode of the file pkg/yqlib/encoder_properties.go. Such manipulation leads to escaping of output. It is possible to launch the attack remotely. The pul…
2.1CVE-2026-1246252026-11-09
A security vulnerability has been detected in PipraPay 3.0.0. Affected by this issue is the function deleteData of the file pp-content/pp-include/pp-functions.php of the component Admin Panel. The manipulation of the argument selected_ids/…
5.1CVE-2026-1245912026-11-09
A vulnerability was detected in Bahleel 0.1.0/0.1.1. Affected is the function fputcsv of the file app/Exporters/CsvExporter.php. The manipulation results in csv injection. The attack may be launched remotely. The project was informed of th…
2.1CVE-2026-1245882026-11-09
A security flaw has been discovered in huggingface finetrainers 0.1.0/0.2.0. The impacted element is the function resolve_component_cls of the file finetrainers/utils/model.py of the component Model Index Handler. Performing a manipulation…
5.5CVE-2026-1245812026-11-09
A vulnerability was determined in itsourcecode Airline Reservation System 1.0. Affected is an unknown function of the file /admin/manage_flight.php. This manipulation of the argument ID causes sql injection. The attack is possible to be ca…
2.1CVE-2026-1245792026-11-09
A vulnerability was determined in aaPanel BillionMail up to 4.9. Affected by this issue is some unknown functionality of the file core/api/relay/v1/relay.go of the component Relay Configuration API. Executing a manipulation of the argument…
2.1CVE-2026-1245712026-11-09
A flaw has been found in SourceCodester Simple CRUD using PHP and FPDF 1.0. Affected by this vulnerability is an unknown functionality of the file app/register.php. Executing a manipulation of the argument firstname can lead to sql injecti…

The newest records naming one of them. Each weakness's page lists them all.

Part of: CAPEC-250 XML Injection

Examples

An attacker can pass XQuery expressions embedded in otherwise standard XML documents. Like SQL injection atta…

An attacker can pass XQuery expressions embedded in otherwise standard XML documents. Like SQL injection attacks, the attacker tunnels through the application entry point to target the resource access layer. The string below is an example of an attacker accessing the accounts.xml to request the service provider send all user names back.

doc(accounts.xml)//user[Name='*']

The attacks that are possible through XQuery are difficult to predict, if the data is not validated prior to executing the XQL.

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