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Weakness · BaseCWE-73

CWE-73: External Control of File Name or Path

Likelihood of exploit: HighKEV-linkedBase

As of 2026-10-05, CWE-73 (External Control of File Name or Path) underlies 14 CVEs tracked by Threadlinqs, 3 of them in the CISA Known Exploited Vulnerabilities catalog, and is cited by 17 tracked threats. MITRE rates its likelihood of exploit as High.

CVEs
14Mapped to CWE-73
CISA KEV
3Exploited in the wild
Critical
1CVSS v3 critical CVEs
Threats
17Tracked campaigns citing it
Likelihood
HighMITRE likelihood of exploit

Last updated:

What is CWE-73?

The product allows user input to control or influence paths or file names that are used in filesystem operations.

This could allow an attacker to access or modify system files or other files that are critical to the application. Path manipulation errors occur when the following two conditions are met: 1. An attacker can specify a path used in an operation on the filesystem. 2. By specifying the resource, the attacker gains a capability that would not otherwise be permitted. For example, the program may give the attacker the ability to overwrite the specified file or run with a configuration controlled by the attacker.

CWE-73 is a base-level weakness in MITRE’s Common Weakness Enumeration, with a MITRE likelihood of exploit of High. Applicable platforms: Not Language-Specific; Unix; Windows; macOS.

Source: MITRE CWE (CWE-73 definition, reproduced verbatim). Counts and linkage below are Threadlinqs data.

Consequences

  • Integrity, Confidentiality — Read Files or Directories, Modify Files or Directories. The application can operate on unexpected files. Confidentiality is violated when the targeted filename is not directly readable by the attacker.
  • Integrity, Confidentiality, Availability — Modify Files or Directories, Execute Unauthorized Code or Commands. The application can operate on unexpected files. This may violate integrity if the filename is written to, or if the filename is for a program or other form of executable code.
  • Availability — DoS: Crash, Exit, or Restart, DoS: Resource Consumption (Other). The application can operate on unexpected files. Availability can be violated if the attacker specifies an unexpected file that the application modifies. Availability can also be affected if the attacker specifies a filename for a large file, or points to a special device or a file that does not have the format that the application expects.

Source: MITRE CWE, common consequences.

How CWE-73 is exploited in the wild

Threadlinqs maps 14 CVEs to CWE-73, published between 2024-11-12 and 2026-10-01. 3 are listed in CISA’s Known Exploited Vulnerabilities catalog, the authoritative record of exploitation in the wild. By CVSS v3 severity the set splits into 1 critical, 7 high, 3 medium. The highest EPSS score in the set is 82.0% (CVE-2025-33053), the modelled probability of exploitation in the next 30 days. 17 tracked threats reference CWE-73 directly or through a CVE it covers; the most recent is “Kiteworks 9.5.1 Patches 126 Vulnerabilities Including Critical Account Takeover in Core and Email Protection Gateway (CVE-2026-102147, CVE-2026-102149)” (2026-10-02). Affected products concentrate in Microsoft (3), AsyncFuncAI (1), JetBrains (1), among 12 vendors in total.

Vulnerabilities (CVEs)

All 14 CVEs mapped to CWE-73, CISA KEV first, then by CVSS score.

Affected vendors

Threat activity

17 tracked threats cite CWE-73:

Mitigations

  • Architecture and Design: When the set of filenames is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames, and reject all other inputs. For example, ID 1 could map to "inbox.txt" and ID 2 could map to "profile.txt". Features such as the ESAPI AccessReferenceMap provide this capability.
  • Architecture and Design, Operation: Run your code in a "jail" or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict all access to files within a particular directory. Examples include the Unix chroot jail and AppArmor. In general, managed code may provide some protection. This may not be a feasible solution, and it only limits the impact to the operating system; the rest of your application may still be subject to compromise. Be careful to avoid CWE-243 and other weaknesses related to jails.
  • Architecture and Design: For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
  • 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
  • Implementation: Use a built-in path canonicalization function (such as realpath() in C) that produces the canonical version of the pathname, which effectively removes ".." sequences and symbolic links (CWE-23, CWE-59).
  • Installation, Operation: Use OS-level permissions and run as a low-privileged user to limit the scope of any successful attack.

Source: MITRE CWE, potential mitigations.

Detection methods (MITRE CWE)

  • Automated Static Analysis: The external control or influence of filenames can often be detected using automated static analysis that models data flow within the product. Automated static analysis might not be able to recognize when proper input validation is being performed, leading to false positives - i.e., warnings that do not have any security consequences or require any code changes.

Source: MITRE CWE, detection methods. Threadlinqs detection rules for the threats above are Blue tier and higher.