The product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could be interpreted as escape, meta, or control character sequences when they are sent to a downstream component.
As data is parsed, an injected/absent/malformed delimiter may cause the process to take unexpected actions.

Primary

Implementation
REALIZATION: This weakness is caused during implementation of an architectural security tactic.

Integrity
Unexpected State

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.)
High

Developers should anticipate that escape, meta and control characters/sequences will be injected/removed/manipulated in the input vectors of their product. Use an appropriate combination of denylists and allowlists to ensure only valid, expected and appropriate input is processed by the system.

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.

Implementation
Output Encoding
While it is risky to use dynamically-generated query strings, code, or commands that mix control and data together, sometimes it may be unavoidable. Properly quote arguments and escape any special characters within those arguments. The most conservative approach is to escape or filter all characters that do not pass an extremely strict allowlist (such as everything that is not alphanumeric or white space). If some special characters are still needed, such as white space, wrap each argument in quotes after the escaping/filtering step. Be careful of argument injection (CWE-88).

Implementation
Input Validation
Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked.

CVE-2002-0542
The mail program processes special "~" escape sequence even when not in interactive mode.
https://www.cve.org/CVERecord?id=CVE-2002-0542

CVE-2000-0703
Setuid program does not filter escape sequences before calling mail program.
https://www.cve.org/CVERecord?id=CVE-2000-0703

CVE-2002-0986
Mail function does not filter control characters from arguments, allowing mail message content to be modified.
https://www.cve.org/CVERecord?id=CVE-2002-0986

CVE-2003-0020
Multi-channel issue. Terminal escape sequences not filtered from log files.
https://www.cve.org/CVERecord?id=CVE-2003-0020

CVE-2003-0083
Multi-channel issue. Terminal escape sequences not filtered from log files.
https://www.cve.org/CVERecord?id=CVE-2003-0083

CVE-2003-0021
Terminal escape sequences not filtered by terminals when displaying files.
https://www.cve.org/CVERecord?id=CVE-2003-0021

CVE-2003-0022
Terminal escape sequences not filtered by terminals when displaying files.
https://www.cve.org/CVERecord?id=CVE-2003-0022

CVE-2003-0023
Terminal escape sequences not filtered by terminals when displaying files.
https://www.cve.org/CVERecord?id=CVE-2003-0023

CVE-2003-0063
Terminal escape sequences not filtered by terminals when displaying files.
https://www.cve.org/CVERecord?id=CVE-2003-0063

CVE-2000-0476
Terminal escape sequences not filtered by terminals when displaying files.
https://www.cve.org/CVERecord?id=CVE-2000-0476

CVE-2001-1556
MFV. (multi-channel). Injection of control characters into log files that allow information hiding when using raw Unix programs to read the files.
https://www.cve.org/CVERecord?id=CVE-2001-1556

Escape, Meta, or Control Character / Sequence

IDS03-J
Do not log unsanitized user input

SFP24
Tainted input to command

Allowed
This CWE entry is at the Variant level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.

PLOVER
2006-07-19
Draft 3
2006-07-19

Eric Dalci
Cigital
2008-07-01
updated Potential_Mitigations, Time_of_Introduction

CWE Content Team
MITRE
2008-09-08
updated Relationships, Taxonomy_Mappings

CWE Content Team
MITRE
2008-10-14
updated Description

CWE Content Team
MITRE
2009-07-27
updated Potential_Mitigations

CWE Content Team
MITRE
2010-04-05
updated Description, Name

CWE Content Team
MITRE
2011-03-29
updated Potential_Mitigations

CWE Content Team
MITRE
2011-06-01
updated Common_Consequences, Observed_Examples, Relationships, Taxonomy_Mappings

CWE Content Team
MITRE
2011-06-27
updated Common_Consequences

CWE Content Team
MITRE
2012-05-11
updated Relationships, Taxonomy_Mappings

CWE Content Team
MITRE
2012-10-30
updated Potential_Mitigations

CWE Content Team
MITRE
2014-07-30
updated Relationships

CWE Content Team
MITRE
2017-05-03
updated Potential_Mitigations

CWE Content Team
MITRE
2017-11-08
updated Applicable_Platforms, Modes_of_Introduction, Relationships

CWE Content Team
MITRE
2019-01-03
updated Relationships, Taxonomy_Mappings

CWE Content Team
MITRE
2019-06-20
updated Related_Attack_Patterns

CWE Content Team
MITRE
2020-02-24
updated Potential_Mitigations, Relationships, Taxonomy_Mappings

CWE Content Team
MITRE
2020-06-25
updated Potential_Mitigations

CWE Content Team
MITRE
2023-01-31
updated Description, Potential_Mitigations

CWE Content Team
MITRE
2023-04-27
updated Relationships

CWE Content Team
MITRE
2023-06-29
updated Mapping_Notes

CWE Content Team
MITRE
2025-12-11
4.19
2025-12-11
updated Detection_Factors, Weakness_Ordinalities

Escape, Meta, or Control Character / Sequence
Failure to Remove Escape, Meta, or Control Character / Sequence
Failure to Sanitize Escape, Meta, or Control Sequences