CWE-88: Improper Neutralization of Argument Delimiters in a Command ('Argument Injection')

The product constructs a string for a command to be executed by a separate component in another control sphere, but it does not properly delimit the intended arguments, options, or switches within that command string.

When creating commands using interpolation into a string, developers may assume that only the arguments/options that they specify will be processed. This assumption may be even stronger when the programmer has encoded the command in a way that prevents separate commands from being provided maliciously, e.g. in the case of shell metacharacters. When constructing the command, the developer may use whitespace or other delimiters that are required to separate arguments when the command. However, if an attacker can provide an untrusted input that contains argument-separating delimiters, then the resulting command will have more arguments than intended by the developer. The attacker may then be able to change the behavior of the command. Depending on the functionality supported by the extraneous arguments, this may have security-relevant consequences.

Consequences

• Confidentiality, Integrity, Availability, Other: Execute Unauthorized Code or Commands, Alter Execution Logic, Read Application Data, Modify Application Data

How to prevent it

• Implementation: Where possible, avoid building a single string that contains the command and its arguments. Some languages or frameworks have functions that support specifying independent arguments, e.g. as an array, which is used to automatically perform the appropriate quoting or escaping while building the command. For example, in PHP, escapeshellarg() can be used to escape a single argument to system(), or exec() can be called with an array of arguments. In C, code can often be refactored from using system() - which accepts a single string - to using exec(), which requires separate function arguments for each parameter.
• Architecture and Design: Understand all the potential areas where untrusted inputs can enter your product: parameters or arguments, cookies, anything read from the network, environment variables, request headers as well as content, URL components, e-mail, files, databases, and any external systems that provide data to the application. Perform input validation at well-defined interfaces.
• 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: Directly convert your input type into the expected data type, such as using a conversion function that translates a string into a number. After converting to the expected data type, ensure that the input's values fall within the expected range of allowable values and that multi-field consistencies are maintained.
• Implementation: Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180, CWE-181). Make sure that your application does not inadvertently decode the same input twice (CWE-174). Such errors could be used to bypass allowlist schemes by introducing dangerous inputs after they have been checked. Use libraries such as the OWASP ESAPI Canonicalization control. Consider performing repeated canonicalization until your input does not change any more. This will avoid double-decoding and similar scenarios, but it might inadvertently modify inputs that are allowed to contain properly-encoded dangerous content.
• Implementation: When exchanging data between components, ensure that both components are using the same character encoding. Ensure that the proper encoding is applied at each interface. Explicitly set the encoding you are using whenever the protocol allows you to do so.
• Implementation: When your application combines data from multiple sources, perform the validation after the sources have been combined. The individual data elements may pass the validation step but violate the intended restrictions after they have been combined.
• Testing: Use dynamic tools and techniques that interact with the product using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The product's operation may slow down, but it should not become unstable, crash, or generate incorrect results.

Recent advisories

• CVE-2026-113708 — Argo CD is a declarative, GitOps continuous delivery tool for Kubernetes.
• GHSA-r825-w8mm-5pxw — launch-editor: Editor CLI flag misinterpretation causing arbitrary command execution for some editors
• GHSA-w889-685w-c8fh — Pillow: Argument Injection in Ghostscript call, potentially leading into RCE
• GHSA-23mf-xhv8-69c2 — GitPython: arbitrary file read via attacker-controlled branch name in `Head.checkout()` (incomplete fix of CVE-2026-78679)
• GHSA-f9j4-qggq-h239 — GitPython Remote.pull() refspec bypasses the --upload-pack unsafe-option guard, enabling arbitrary command execution
• GHSA-rw58-wc66-99g4 — Duplicate Advisory: GitPython 3.1.59: --no-index bypasses diff unsafe-option protections and enables a blind local-file content oracle
• CVE-2026-86060 — RouterOS contains an argument-handling flaw in the SSH login path involving usernames that begin with a prohibited character, allowing for the trusted RouterOS…
• GHSA-m4rf-3fr8-xwx3 — NLTK: JVM argument injection bypass via per-call options in the NLTK Stanford wrappers (incomplete fix of CVE-2026-12841)
• GHSA-3wxw-xv34-2frg — GitPython: TagReference.create positional reference bypasses kwargs-only --file guard, enabling arbitrary file read (incomplete fix of 3af0c251)
• GHSA-5xxx-qhh7-9287 — GitPython: Incomplete unsafe_git_revision_options denylist omits --contents/-S, enabling arbitrary file read via Repo.blame()
• GHSA-284h-m62q-gf8w — GitPython: Dormant multi-line git-config values are corrupted into live injected directives (e.g. core.hooksPath) on any unrelated GitConfigParser write, enabling RCE
• GHSA-7j5w-7r7x-9v27 — CodeWhale: Argument Injection in `git_show` Tool Allows Arbitrary File Write Without Approval
• GHSA-c6mw-8xh8-gpq6 — CodeWhale: Argument Injection in `git_blame` Tool Allows Arbitrary File Read Without Approval
• GHSA-wvpp-8hx9-p66j — GitPython: Unsafe git option guard bypass via split_single_char_options=False short-option token smuggling enables command execution
• GHSA-jm78-9fvv-mhgr — GitPython: git-config OPTION-name injection via =/#/whitespace bypasses name validator, enabling forged core.sshCommand/hooksPath (RCE)

All advisories for CWE-88