CWE-785: Use of Path Manipulation Function without Maximum-sized Buffer

Code Examples & CVEs

Demonstrative Examples

In this example the function creates a directory named "output\<name>" in the current directory and returns a heap-allocated copy of its name.

For most values of the current directory and the name parameter, this function will work properly. However, if the name parameter is particularly long, then the second call to PathAppend() could overflow the outputDirectoryName buffer, which is smaller than MAX_PATH bytes.

BadC

char *createOutputDirectory(char *name) {                         char outputDirectoryName[128];if (getCurrentDirectory(128, outputDirectoryName) == 0) {return null;}if (!PathAppend(outputDirectoryName, "output")) {return null;}if (!PathAppend(outputDirectoryName, name)) {                                                                 return null;                            }if (SHCreateDirectoryEx(NULL, outputDirectoryName, NULL) != ERROR_SUCCESS) {                                                                 return null;                            }return StrDup(outputDirectoryName);                      }

Source-backed guidance

Additional facts reviewed against primary or authoritative security sources.

Verify controls for CWE-785 with SSDF evidence

Use NIST SSDF verification and vulnerability-response practices to detect CWE-785, Use of Path Manipulation Function without Maximum-sized Buffer, throughout the product lifecycle. Derive review questions, static or dynamic checks, and negative tests from the CWE's causal behavior; define the components and lifecycle stages each check covers; and retain findings with enough evidence to distinguish the root cause from symptoms and impacts. Track escapes and false negatives, then improve the verification plan after every confirmed occurrence.

NIST SP 800-218 Secure Software Development Framework — National Institute of Standards and Technology

Address Use of Path Manipulation Function without Maximum-sized Buffer during Implementation

MITRE associates mitigation with Implementation; documented detection approaches include Automated Static Analysis; recorded impacts include Modify Memory, Execute Unauthorized Code or Commands, and DoS: Crash, Exit, or Restart. Use these source-defined anchors to turn CWE-785 into implementation, review, and verification checks for the affected component.

CWE-785: Use of Path Manipulation Function without Maximum-sized Buffer — MITRE CWE

Triage CWE-785 against known exploitation evidence

Use CISA's Known Exploited Vulnerabilities catalog to test whether a vulnerability mapped to CWE-785, Use of Path Manipulation Function without Maximum-sized Buffer, has evidence of exploitation in the wild. Confirm the CVE-to-CWE root-cause mapping independently before attaching the example, then capture the affected product, required action, and remediation deadline. A missing KEV match is not evidence that the weakness is unexploited, and a KEV entry must not be generalized to every occurrence of this CWE.

Known Exploited Vulnerabilities Catalog — Cybersecurity and Infrastructure Security Agency

Apply precise root-cause mapping to CWE-785

Apply MITRE's full root-cause mapping guidance when using CWE-785, Use of Path Manipulation Function without Maximum-sized Buffer. Separate weakness language from attacker prerequisites and technical impact, check the entry's abstraction and vulnerability-mapping notes, and prefer the most specific Base or Variant supported by the evidence. Record the rejected alternatives and require an independent review before the mapping is used for remediation trends or program metrics.

CVE to CWE Root Cause Mapping Guidance — MITRE CWE

Validate CWE-785 with root-cause mapping checks

Apply MITRE's root-cause mapping quick tips to CWE-785, Use of Path Manipulation Function without Maximum-sized Buffer. Confirm the finding describes the causal weakness rather than an impact or attack pattern, compare the abstraction and mapping notes with plausible alternatives, and have a second reviewer challenge the selection. Preserve the evidence and reasoning so recurring defects can be measured against one consistent identifier.

CVE to CWE Root Cause Mapping Quick Tips — MITRE CWE

Frequently Asked Questions

What is CWE-785: Use of Path Manipulation Function without Maximum-sized Buffer?+

CWE-785: Use of Path Manipulation Function without Maximum-sized Buffer is a Common Weakness Enumeration (CWE) entry maintained by MITRE. The product invokes a function for normalizing paths or file names, but it provides an output buffer that is smaller than the maximum possible size, such as PATH_MAX. Passing an inadequately-sized output buffer to a path manipulation function can result in a buffer overflow. Such functions include realpath(), readlink(), PathAppend(), and others.

What are the security consequences of Use of Path Manipulation Function without Maximum-sized Buffer?+

If exploited, CWE-785 (Use of Path Manipulation Function without Maximum-sized Buffer) it can compromise Integrity, Confidentiality and Availability, leading to outcomes such as Modify Memory, Execute Unauthorized Code or Commands and DoS: Crash, Exit, or Restart.

How do you prevent or mitigate Use of Path Manipulation Function without Maximum-sized Buffer?+

Recommended mitigations for CWE-785 include: Always specify output buffers large enough to handle the maximum-size possible result from path manipulation functions.

Which programming languages are affected by Use of Path Manipulation Function without Maximum-sized Buffer?+

CWE-785 commonly affects C and C++. Note that weaknesses are often language-agnostic patterns, so secure coding practices apply broadly.

What is the difference between a CWE and a CVE?+

A CWE (Common Weakness Enumeration) like CWE-785 describes a category of software weakness — the underlying flaw type. A CVE (Common Vulnerabilities and Exposures) identifies a specific, real-world vulnerability in a particular product. In short, a CWE is the kind of mistake, and a CVE is an instance of that mistake being found in software.

CWE-785: Use of Path Manipulation Function without Maximum-sized Buffer

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