CWE WEAKNESSES  /  CWE-150

CWE-150

Improper Neutralization of Escape, Meta, or Control Sequences

What it is

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.

Impact

Mitigations

• 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]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 r
• [Implementation] 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 whit
• [Implementation] 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.
• [Implementation] When using output from an LLM, neutralize or strip escape codes before redirecting output to the terminal or other rendering engine that would process the codes. The neutralization could require that the character be printable and/or allowable whitespace, such as a carriage return or newline. Be deliberate about what to allow.
• [Build and Compilation] When using an LLM: during tokenizer training, suppress escape codes from the tokenizer's vocabulary. Depending on context, this could be accomplished by removing the codes from input to the tokenizer, or removing the map from the string to its token ID. It is generally unlikely that this removal would adversely affect the quality or correctness of what is generated, e.g. advice requests for termin

Real-world CVE examples

• CVE-2024-27936 — Chain: JavaScript-based application removes ANSI escape sequences in a dialog that asks permission for a particular file, causing the wrong filename to be visua
• CVE-2002-0542 — The mail program processes special "~" escape sequence even when not in interactive mode.
• CVE-2000-0703 — Setuid program does not filter escape sequences before calling mail program.
• CVE-2002-0986 — Mail function does not filter control characters from arguments, allowing mail message content to be modified.
• CVE-2003-0020 — Multi-channel issue. Terminal escape sequences not filtered from log files.
• CVE-2003-0083 — Multi-channel issue. Terminal escape sequences not filtered from log files.
• CVE-2003-0021 — Terminal escape sequences not filtered by terminals when displaying files.
• CVE-2003-0022 — Terminal escape sequences not filtered by terminals when displaying files.
• CVE-2003-0023 — Terminal escape sequences not filtered by terminals when displaying files.
• CVE-2003-0063 — Terminal escape sequences not filtered by terminals when displaying files.
• CVE-2000-0476 — Terminal escape sequences not filtered by terminals when displaying files.
• 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.

Related weaknesses

Source: MITRE CWE. View on cwe.mitre.org →