CWEweakness
CWE-38 Path Traversal: '\absolute\pathname\here'
- Abstraction
- Variant
- Structure
- Simple
- Status
- Draft
- Languages
- Not Language-Specific
- CWE version
- 5.0
Description
The product accepts input in the form of a backslash absolute path ('\absolute\pathname\here') without appropriate neutralization.
Common consequences
• Confidentiality, Integrity: Read Files or Directories, Modify Files or Directories — An attacker can traverse the file system to unintended locations to read or modify arbitrary files.
Potential mitigations
• [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.
When validating filenames, use stringent allowlists that limit the character set to be used. If feasible, only allow a single "." character in the filename to avoid weaknesses such as CWE-23, and exclude directory separators such as "/" to avoid CWE-36. Use a list of allowable file extensions, which will help to avoid CWE-434.
Do not rely exclusively on a filtering mechanism that removes potentially dangerous characters. This is equivalent to a denylist, which may be incomplete (CWE-184). For example, filtering "/" is insufficient protection if the filesystem also supports the use of "\" as a directory separator. Another possible error could occur when the filtering is applied in a way that still produces dangerous data (CWE-182). For example, if "../" sequences are removed from the ".../...//" string in a sequential fashion, two instances of "../" would be removed from the original string, but the remaining characters would still form the "../" string.
• [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.
Detection methods
• Automated Static Analysis: Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)
Observed examples
• CVE-1999-1263: Mail client allows remote attackers to overwrite arbitrary files via an e-mail message containing a uuencoded attachment that specifies the full pathname for the file to be modified.
• CVE-2003-0753: Remote attackers can read arbitrary files via a full pathname to the target file in config parameter.
• CVE-2002-1525: Remote attackers can read arbitrary files via an absolute pathname.
Related
Observed example · CVE (3)
- CVE-2003-0753 nphpd.php in newsPHP 216 and earlier allows remote attackers to read arbitrary files via a full pathname to the target file in the… vulnerability
- CVE-1999-1263 Metamail before 2.7-7.2 allows remote attackers to overwrite arbitrary files via an e-mail message containing a uuencoded attachment that… vulnerability
- CVE-2002-1525 Directory traversal vulnerability in ASTAware SearchDisk engine for Sun ONE Starter Kit 2.0 allows remote attackers to read arbitrary files… vulnerability
Child of · CWE (1)
- CWE-36 Absolute Path Traversal weakness
Referenced by CVE · weakness (1)
- CVE-2026-9507 A session fixation vulnerability has been identified in osTicket v1.18.2. vulnerability