CWE-41: Improper Resolution of Path Equivalence
The product is vulnerable to file system contents disclosure through path equivalence. Path equivalence involves the use of special characters in file and directory names. The associated manipulations are intended to generate multiple names for the same object.
Last updated
Overview
Path equivalence is usually employed in order to circumvent access controls expressed using an incomplete set of file name or file path representations. This is different from path traversal, wherein the manipulations are performed to generate a name for a different object.
Real-world CVEs
32 recorded CVEs are caused by CWE-41 (Improper Resolution of Path Equivalence). The highest-severity and most recent are shown first. 11 new CWE-41 CVEs have been recorded so far in 2026 (15 in 2025).
- CVE-2025-21332
MapUrlToZone Security Feature Bypass Vulnerability
High · CVSS 8.8 · EPSS 73th2025-01-14 - CVE-2026-57441
MCPVault: PathFilter restricted-directory deny-list bypass via case and trailing dot/space equivalence
High · CVSS 8.4 · EPSS 9th2026-09-15 - CVE-2026-49401
Deno Permission Bypass via Unicode Normalization Mismatch on macOS (APFS)
High · CVSS 8.4 · EPSS 9th2026-06-23 - CVE-2026-5816
Improper Resolution of Path Equivalence in GitLab
High · CVSS 8.1 · EPSS 47th2026-04-22 - CVE-2025-24470High · CVSS 8.1 · EPSS 70th2025-02-11
- CVE-2025-43298High · CVSS 7.8 · EPSS 15th2025-09-15
- CVE-2024-30073
Windows Security Zone Mapping Security Feature Bypass Vulnerability
High · CVSS 7.8 · EPSS 59th2024-09-10 - CVE-2023-36396High · CVSS 7.8 · EPSS 76th2023-11-14
- CVE-2026-72835
filebrowser before v2.63.21 Access Rule Bypass via Path Canonicalization
High · CVSS 7.6 · EPSS 41th2026-08-14 - CVE-2026-23674
MapUrlToZone Security Feature Bypass Vulnerability
High · CVSS 7.5 · EPSS 68th2026-03-10 - CVE-2024-8765High · CVSS 7.3 · EPSS 56th2025-03-20
- CVE-2026-34510
OpenClaw < 2026.3.22 - Remote File URL Acceptance in Windows Media Loaders
Medium · CVSS 6.9 · EPSS 38th2026-04-01
Showing 12 of 32 recorded CWE-41 CVEs. Get an alert for each new one, with AI-written analysis and fixes.
Monitor CWE-41 vulnerabilitiesCommon consequences
What can happen when CWE-41 is exploited.
Read Files or Directories, Modify Files or Directories, Bypass Protection Mechanism
Affects: Confidentiality, Integrity, Access Control
An attacker may be able to traverse the file system to unintended locations and read or overwrite the contents of unexpected files. If the files are used for a security mechanism than an attacker may be able to bypass the mechanism.
How it happens
When it is introduced
Typically introduced during these phases of the software lifecycle.
How to prevent it
Practical mitigations for CWE-41, grouped by where in the lifecycle they apply.
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.
Use and specify an output encoding that can be handled by the downstream component that is reading the output. Common encodings include ISO-8859-1, UTF-7, and UTF-8. When an encoding is not specified, a downstream component may choose a different encoding, either by assuming a default encoding or automatically inferring which encoding is being used, which can be erroneous. When the encodings are inconsistent, the downstream component might treat some character or byte sequences as special, even if they are not special in the original encoding. Attackers might then be able to exploit this discrepancy and conduct injection attacks; they even might be able to bypass protection mechanisms that assume the original encoding is also being used by the downstream component.
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.
How to detect it
Automated Static Analysis - Binary or Bytecode
According to SOAR [REF-1479], the following detection techniques may be useful:
Effectiveness: SOAR Partial
Manual Static Analysis - Binary or Bytecode
According to SOAR [REF-1479], the following detection techniques may be useful:
Effectiveness: SOAR Partial
Dynamic Analysis with Automated Results Interpretation
According to SOAR [REF-1479], the following detection techniques may be useful:
Effectiveness: SOAR Partial
Dynamic Analysis with Manual Results Interpretation
According to SOAR [REF-1479], the following detection techniques may be useful:
Effectiveness: SOAR Partial
Manual Static Analysis - Source Code
According to SOAR [REF-1479], the following detection techniques may be useful:
Effectiveness: High
Automated Static Analysis - Source Code
According to SOAR [REF-1479], the following detection techniques may be useful:
Effectiveness: SOAR Partial
Architecture or Design Review
According to SOAR [REF-1479], the following detection techniques may be useful:
Effectiveness: High
Illustrative examples
Real CVEs that MITRE cites as examples of this weakness.
- CVE-2000-1114 — Source code disclosure using trailing dot
- CVE-2002-1986 — Source code disclosure using trailing dot
- CVE-2004-2213 — Source code disclosure using trailing dot or trailing encoding space "%20"
- CVE-2005-3293 — Source code disclosure using trailing dot
- CVE-2004-0061 — Bypass directory access restrictions using trailing dot in URL
- CVE-2000-1133 — Bypass directory access restrictions using trailing dot in URL
- CVE-2001-1386 — Bypass check for ".lnk" extension using ".lnk."
- CVE-2001-0693 — Source disclosure via trailing encoded space "%20"
- CVE-2001-0778 — Source disclosure via trailing encoded space "%20"
- CVE-2001-1248 — Source disclosure via trailing encoded space "%20"
- CVE-2004-0280 — Source disclosure via trailing encoded space "%20"
- CVE-2005-0622 — Source disclosure via trailing encoded space "%20"
- CVE-2005-1656 — Source disclosure via trailing encoded space "%20"
- CVE-2002-1603 — Source disclosure via trailing encoded space "%20"
- CVE-2001-0054 — Multi-Factor Vulnerability (MFV). directory traversal and other issues in FTP server using Web encodings such as "%20"; certain manipulations have unusual side effects.
- CVE-2002-1451 — Trailing space ("+" in query string) leads to source code disclosure.
- CVE-2000-0293 — Filenames with spaces allow arbitrary file deletion when the product does not properly quote them; some overlap with path traversal.
- CVE-2001-1567 — "+" characters in query string converted to spaces before sensitive file/extension (internal space), leading to bypass of access restrictions to the file.
- CVE-2002-0253 — Overlaps infoleak
- CVE-2001-0446 — Application server allows remote attackers to read source code for .jsp files by appending a / to the requested URL.
- CVE-2004-0334 — Bypass Basic Authentication for files using trailing "/"
- CVE-2001-0893 — Read sensitive files with trailing "/"
- CVE-2001-0892 — Web server allows remote attackers to view sensitive files under the document root (such as .htpasswd) via a GET request with a trailing /.
- CVE-2004-1814 — Directory traversal vulnerability in server allows remote attackers to read protected files via .. (dot dot) sequences in an HTTP request.
- CVE-2002-1483 — Read files with full pathname using multiple internal slash.
- CVE-1999-1456 — Server allows remote attackers to read arbitrary files via a GET request with more than one leading / (slash) character in the filename.
- CVE-2004-0578 — Server allows remote attackers to read arbitrary files via leading slash (//) characters in a URL request.
- CVE-2002-0275 — Server allows remote attackers to bypass authentication and read restricted files via an extra / (slash) in the requested URL.
- CVE-2004-1032 — Product allows local users to delete arbitrary files or create arbitrary empty files via a target filename with a large number of leading slash (/) characters.
- CVE-2002-1238 — Server allows remote attackers to bypass access restrictions for files via an HTTP request with a sequence of multiple / (slash) characters such as http://www.example.com///file/.
- CVE-2004-1878 — Product allows remote attackers to bypass authentication, obtain sensitive information, or gain access via a direct request to admin/user.pl preceded by // (double leading slash).
- CVE-2005-1365 — Server allows remote attackers to execute arbitrary commands via a URL with multiple leading "/" (slash) characters and ".." sequences.
- CVE-2000-1050 — Access directory using multiple leading slash.
- CVE-2001-1072 — Bypass access restrictions via multiple leading slash, which causes a regular expression to fail.
- CVE-2004-0235 — Archive extracts to arbitrary files using multiple leading slash in filenames in the archive.
- CVE-2002-1078 — Directory listings in web server using multiple trailing slash
- CVE-2004-0847 — web framework for .NET allows remote attackers to bypass authentication for .aspx files in restricted directories via a request containing a (1) "\" (backslash) or (2) "%5C" (encoded backslash)
- CVE-2000-0004 — Server allows remote attackers to read source code for executable files by inserting a . (dot) into the URL.
- CVE-2002-0304 — Server allows remote attackers to read password-protected files via a /./ in the HTTP request.
- CVE-1999-1083 — Possibly (could be a cleansing error)
- CVE-2004-0815 — "/./////etc" cleansed to ".///etc" then "/etc"
- CVE-2002-0112 — Server allows remote attackers to view password protected files via /./ in the URL.
- CVE-2004-0696 — List directories using desired path and "*"
- CVE-2002-0433 — List files in web server using "*.ext"
- CVE-2001-1152 — Proxy allows remote attackers to bypass denylist restrictions and connect to unauthorized web servers by modifying the requested URL, including (1) a // (double slash), (2) a /SUBDIR/.. where the desired file is in the parentdir, (3) a /./, or (4) URL-encoded characters.
- CVE-2000-0191 — application check access for restricted URL before canonicalization
- CVE-2005-1366 — CGI source disclosure using "dirname/../cgi-bin"
- CVE-1999-0012 — Multiple web servers allow restriction bypass using 8.3 names instead of long names
- CVE-2001-0795 — Source code disclosure using 8.3 file name.
- CVE-2005-0471 — Multi-Factor Vulnerability. Product generates temporary filenames using long filenames, which become predictable in 8.3 format.
Terminology & mappings
Mapped taxonomies
- PLOVER: Path Equivalence
- CERT C Secure Coding: Canonicalize path names originating from untrusted sources (FIO02-C)
Attack patterns
CAPEC attack patterns that exploit this weakness.
Frequently asked questions
Common questions about CWE-41.
- What is CWE-41?
- The product is vulnerable to file system contents disclosure through path equivalence. Path equivalence involves the use of special characters in file and directory names. The associated manipulations are intended to generate multiple names for the same object.
- What CVEs are caused by CWE-41?
- 32 recorded CVEs are attributed to CWE-41, including CVE-2025-21332, CVE-2026-57441, CVE-2026-49401.
- How do you prevent CWE-41?
- 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.
- How is CWE-41 detected?
- Automated Static Analysis - Binary or Bytecode: According to SOAR [REF-1479], the following detection techniques may be useful:
- What are the consequences of CWE-41?
- Exploiting CWE-41 can lead to: Read Files or Directories, Modify Files or Directories, Bypass Protection Mechanism.
- Is CWE-41 actively exploited?
- 32 recorded CVEs are caused by CWE-41; none are currently in CISA's KEV catalog of actively exploited flaws.
References
- MITRE CWE definition (CWE-41) (opens in a new tab)
- CWE-41 vulnerabilities on NVD (opens in a new tab)
- Learn: What is a CWE?
Weakness data is sourced from the MITRE CWE catalog (v4.20). CVE associations are aggregated and kept current by RadicalNotion.AI.
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