CWE-93

Base Abstraction Level
Pillar — Highest-level weakness category
Class — Abstract, language-independent
Base — Specific enough to detect
Variant — Tied to specific technology
Compound — Requires multiple weaknesses Draft MITRE CWE Status
Stable — Fully reviewed and complete
Draft — Under development, may change
Incomplete — Partially defined by MITRE
Deprecated — No longer recommended
Obsolete — Replaced by another CWE
Improper Neutralization of CRLF Sequences ('CRLF Injection')

Description

The product uses CRLF (carriage return line feeds) as a special element, e.g. to separate lines or records, but it does not neutralize or incorrectly neutralizes CRLF sequences from inputs.

Top Monitored CVEs

CVE-2025-61884
HIGH KEV
7.5 97.8%
2025-10-12
CVE-2021-39172
HIGH
8.8 29.2%
2021-08-27

Consequences

Integrity — Modify Application Data

Mitigations

Phase: Implementation

Avoid using CRLF as a special sequence.

Phase: Implementation

Appropriately filter or quote CRLF sequences in user-controlled input.

Detection

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.)