CAPEC-146

How the attack unfolds

1. Explore

   The attacker looks for a way in.

   1. [Determine if XML schema is local or remote] Because this attack differs slightly if the target uses remote XML schemas versus local schemas, the adversary first needs to determine which of the two are used.

2. Experiment

   They probe what they found.

   2. [Gain access to XML schema] The adversary gains access to the XML schema so that they can modify the contents.

      2 techniques

      • For a local scenario, the adversary needs access to the machine that the schema is located on and needs to gain permissions to alter the contents of the file.
      • For a remote scenario, the adversary needs to be able to sniff HTTP traffic that contains an XML schema.

3. Exploit

   They carry out the attack.

   3. [Poison XML schema] Once the adversary gains access to the XML schema, they will alter it to achieve a desired effect. Locally, they can simply modify the file. For remote schemas, the adversary will alter the schema in transit by performing an adversary in the middle attack.

      3 techniques

      • Cause a denial of service by modifying the schema so that it does not contain required information for subsequent processing. For example, the unaltered schema may require a @name attribute in all submitted documents. If the adversary removes this attribute from the schema then documents created using the new grammar may lack this field, which may cause the processing application to enter an unexpected state or record incomplete data.
      • Manipulation of the data types described in the schema may affect the results of calculations. For example, a float field could be changed to an int field.
      • Change the encoding defined in the schema for certain fields allowing the contents to bypass filters that scan for dangerous strings. For example, the modified schema might use a URL encoding instead of ASCII, and a filter that catches a semicolon (;) might fail to detect its URL encoding (%3B).

Prerequisites

• Some level of access to modify the target schema.

• The schema used by the target application must be improperly secured against unauthorized modification and manipulation.

Resources required

• Access to the schema and the knowledge and ability modify it. Ability to replace or redirect access to the modified schema.

Consequences

Mitigations

• Design: Protect the schema against unauthorized modification.

• Implementation: For applications that use a known schema, use a local copy or a known good repository instead of the schema reference supplied in the XML document. Additionally, ensure that the proper permissions are set on local files to avoid unauthorized modification.

• Implementation: For applications that leverage remote schemas, use the HTTPS protocol to prevent modification of traffic in transit and to avoid unauthorized modification.

Weaknesses it exploits

• CWE-15 External Control of System or Configuration Setting
• CWE-472 External Control of Assumed-Immutable Web Parameter

Recent CVEs with these weaknesses

1. 8.8CVE-2026-132922026-11-04

   IBM MQ 9.2.0.0 through 9.2.0.44 LTS, 9.3.0.0 through 9.3.0.42 LTS, 9.4.0.0 through 9.4.0.26 LTS, 9.4.0.0 through 9.4.5.1 CD, and 10.0.0.0 through 10.0.0.5 LTS and CD could allow an authenticated attacker to execute arbitrary code by inject…

2. 7.1CVE-2026-1216142026-11-03

   Docker Sandboxes versions 0.31.0 before 0.50.0 do not neutralize repository-controlled Git configuration when running certain host-side Git commands. An attacker who can modify a host repository's Git configuration, for example through a d…

3. 8.7CVE-2026-1214272026-11-03

   AzuraCast through 0.23.8 fails to remove frontend_config.custom_config in PUT /station/{id}/profile/edit for users lacking the Manage station broadcasting permission, and the stored JSON is written verbatim as key=value lines into the Shou…

4. 7.1CVE-2026-1154502026-10-22

   External Control of Assumed-Immutable Web Parameter (CWE-472) in the cart and checkout flow of MarcosCamara01 Ecommerce Template allows an authenticated user with no special privileges to be charged the price of one product while placing a…

5. 7.1CVE-2026-164532026-10-16

   Mattermost versions 11.10.x <= 11.10.0, 11.7.x <= 11.7.9, 11.9.x <= 11.9.1, 11.8.x <= 11.8.5 fail to verify the integrity of the SAML RelayState POST parameter which allows an authenticated SAML user to join any team, including invite-only…

6. 8.1CVE-2026-1114472026-10-16

   Wheels 1.1 through 4.1.2 resolves nestedProperties() records by posted primary key without checking that they belong to the parent being saved. A user able to submit a nested form for their own parent can update and reassign another parent…

7. 8.3CVE-2026-774702026-10-15

   Lychee is a free, open-source photo-management tool. Prior to 7.7.1, the Supporter or Pro webshop POST /api/v2/Shop/Checkout/Process flow accepts an unrestricted additional_data array and CheckoutService::preparePurchaseParameters() merges…

8. 4.6CVE-2025-684032026-10-15

   An external control of system or configuration setting vulnerability has been reported to affect QuRouter. If a local attacker gains an administrator account, they can then exploit the vulnerability to modify data on the system. We have a…

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

Related attack patterns

Part of

• CAPEC-271 Schema Poisoning

Examples

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