What CVEs are caused by CWE-91?

74 recorded CVEs are attributed to CWE-91, including CVE-2020-0646, CVE-2021-4140, CVE-2025-66034. 1 are listed in CISA's Known Exploited Vulnerabilities (KEV) catalog.

Is CWE-91 part of the OWASP Top 10?

CWE-91 maps to OWASP Top Ten 2007: Injection Flaws (A2) in the OWASP security taxonomy.

Is CWE-91 actively exploited?

Yes. 1 CWE-91 vulnerabilities are in CISA's KEV catalog of actively exploited flaws, out of 74 recorded CVEs.

Base weakness

Draft

CWE-91: XML Injection (aka Blind XPath Injection)

The product does not properly neutralize special elements that are used in XML, allowing attackers to modify the syntax, content, or commands of the XML before it is processed by an end system.

Last updated May 1, 2026

Recorded CVEs

With this primary weakness

KEVs

In the CISA KEV catalog

Not rated

Likelihood of exploit

Per MITRE

Base

Abstraction

MITRE classification

Overview

Within XML, special elements could include reserved words or characters such as " ", """, and "&", which could then be used to add new data or modify XML syntax.

Real-world CVEs

74 recorded CVEs are caused by CWE-91 (XML Injection (aka Blind XPath Injection)), including 1 in CISA's KEV (Known Exploited Vulnerabilities) catalog. KEVs are shown first. 22 new CWE-91 CVEs have been recorded so far in 2026 (11 in 2025).

Showing 12 of 74 recorded CWE-91 CVEs. Track new ones as they are published and get AI-written analysis and fixes.

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Common consequences

What can happen when CWE-91 is exploited.

Execute Unauthorized Code or Commands, Read Application Data, Modify Application Data

Affects: Confidentiality, Integrity, Availability

How it happens

When it is introduced

Typically introduced during these phases of the software lifecycle.

Implementation

How to prevent it

Practical mitigations for CWE-91, grouped by where in the lifecycle they apply.

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.

When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue."

Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.

How to detect it

Automated Static Analysis

Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)

Effectiveness: High

Terminology & mappings

Mapped taxonomies

PLOVER: XML injection (aka Blind Xpath injection)
OWASP Top Ten 2007: Injection Flaws (A2) — CWE More Specific fit
OWASP Top Ten 2004: Injection Flaws (A6) — CWE More Specific fit
WASC: XML Injection (23)
Software Fault Patterns: Tainted input to command (SFP24)

Attack patterns

CAPEC attack patterns that exploit this weakness.

Frequently asked questions

Common questions about CWE-91.

What is CWE-91?: The product does not properly neutralize special elements that are used in XML, allowing attackers to modify the syntax, content, or commands of the XML before it is processed by an end system.
What CVEs are caused by CWE-91?: 74 recorded CVEs are attributed to CWE-91, including CVE-2020-0646, CVE-2021-4140, CVE-2025-66034. 1 are listed in CISA's Known Exploited Vulnerabilities (KEV) catalog.
Is CWE-91 part of the OWASP Top 10?: CWE-91 maps to OWASP Top Ten 2007: Injection Flaws (A2) in the OWASP security taxonomy.
How do you prevent CWE-91?: 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.
How is CWE-91 detected?: Automated Static Analysis: Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)
What are the consequences of CWE-91?: Exploiting CWE-91 can lead to: Execute Unauthorized Code or Commands, Read Application Data, Modify Application Data.
Is CWE-91 actively exploited?: Yes. 1 CWE-91 vulnerabilities are in CISA's KEV catalog of actively exploited flaws, out of 74 recorded CVEs.

References

Weakness data is sourced from the MITRE CWE catalog (v4.20). CVE associations are aggregated and kept current by RadicalNotion.AI.

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