CWE-147
Improper Neutralization of Input Terminators
Extended description
For example, a "." in SMTP signifies the end of mail message data, whereas a null character can be used for the end of a string.
Common consequences1
- IntegrityUnexpected State
Potential mitigations4
Developers should anticipate that terminators 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 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
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
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.
Relationships1
- ChildOfCWE-138
CVEs referencing this CWE6
| CVE | Description | Severity | EPSS | Flags | Modified |
|---|---|---|---|---|---|
| CVE-2021-38189 | An issue was discovered in the lettre crate before 0.9.6 for Rust. In an e-mail message body, an attacker can place a . character after two <CR><LF> sequences and then inject arbitrary SMTP commands. | CRITICAL9.8 | 1.49%p71 | 2024-11-21 | |
| CVE-2024-52006 | Git is a fast, scalable, distributed revision control system with an unusually rich command set that provides both high-level operations and full access to internals. Git defines a line-based protocol that is used to exchange information between Git and Git credential helpers. Some ecosystems (most notably, .NET and node.js) interpret single Carriage Return characters as newlines, which renders the protections against CVE-2020-5260 incomplete for credential helpers that treat Carriage Returns in this way. This issue has been addressed in commit `b01b9b8` which is included in release versions v2.48.1, v2.47.2, v2.46.3, v2.45.3, v2.44.3, v2.43.6, v2.42.4, v2.41.3, and v2.40.4. Users are advised to upgrade. Users unable to upgrade should avoid cloning from untrusted URLs, especially recursive clones. | HIGH7.5 | 1.02%p59 | 2025-12-18 | |
| CVE-2025-7962 | In Jakarta Mail 2.0.2 it is possible to preform a SMTP Injection by utilizing the \r and \n UTF-8 characters to separate different messages. | HIGH7.5 | 0.71%p48 | 2026-04-16 | |
| CVE-2024-50349 | Git is a fast, scalable, distributed revision control system with an unusually rich command set that provides both high-level operations and full access to internals. When Git asks for credentials via a terminal prompt (i.e. without using any credential helper), it prints out the host name for which the user is expected to provide a username and/or a password. At this stage, any URL-encoded parts have been decoded already, and are printed verbatim. This allows attackers to craft URLs that contain ANSI escape sequences that the terminal interpret to confuse users e.g. into providing passwords for trusted Git hosting sites when in fact they are then sent to untrusted sites that are under the attacker's control. This issue has been patch via commits `7725b81` and `c903985` which are included in release versions v2.48.1, v2.47.2, v2.46.3, v2.45.3, v2.44.3, v2.43.6, v2.42.4, v2.41.3, and v2.40.4. Users are advised to upgrade. Users unable to upgrade should avoid cloning from untrusted URLs, especially recursive clones. | MEDIUM4.7 | 0.64%p46 | 2025-12-18 | |
| CVE-2024-52505 | matrix-appservice-irc is a Node.js IRC bridge for the Matrix messaging protocol. The provisioning API of the matrix-appservice-irc bridge up to version 3.0.2 contains a vulnerability which can lead to arbitrary IRC command execution as the bridge IRC bot. The vulnerability has been patched in matrix-appservice-irc version 3.0.3. | MEDIUM5.4 | 0.37%p29 | 2026-04-15 | |
| CVE-2023-4393 | HTML and SMTP injections on the registration page of LiquidFiles versions 3.7.13 and below, allow an attacker to perform more advanced phishing attacks against an organization. | MEDIUM6.1 | 0.31%p22 | 2024-11-21 |