The WebDAV extension in Microsoft Internet Information Services (IIS) 5.1 and 6.0 allows remote attackers to bypass URI-based protection mec
The WebDAV extension in Microsoft Internet Information Services (IIS) 5.1 and 6.0 allows remote attackers to bypass URI-based protection mechanisms, and list folders or read, create, or modify files, via a %c0%af (Unicode / character) at an arbitrary position in the URI, as demonstrated by inserting %c0%af into a "/protected/" initial pathname component to bypass the password protection on the protected\ folder, aka "IIS 5.1 and 6.0 WebDAV Authentication Bypass Vulnerability," a different vulnerability than CVE-2009-1122.
- Published
- Jun 10, 2009
- Updated
- Jun 16, 2026
- EPSS
- 98.1% · 100th percentile
- CWE
- CWE-287
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Report tools
Action score
59
Plan
Add it to your regular patch cycle.
- CVSS
- 30 / 40 · 7.5 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 29 / 30 · 98.1%
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| microsoft | internet information services | cpe:2.3:a:microsoft:internet_information_services |
| microsoft | windows xp | cpe:2.3:o:microsoft:windows_xp |
| microsoft | windows server 2003 | cpe:2.3:o:microsoft:windows_server_2003 |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- microsoft internet information services5.1
- microsoft internet information services6.0
Same product
microsoft: all recordsOther highest-scoring records for the same primary product.
- CVE-2017-7269Buffer overflow in the ScStoragePathFromUrl function in the WebDAV service in Internet Information Services (IIS) 6.0 in Microsoft Windows SKEV99Now
- CVE-2010-3972Heap-based buffer overflow in the TELNET_STREAM_CONTEXT::OnSendData function in ftpsvc.dll in Microsoft FTP Service 7.0 and 7.5 for Internet68This week
- CVE-2007-2815The "hit-highlighting" functionality in webhits.dll in Microsoft Internet Information Services (IIS) Web Server 5.0 only uses Windows NT ACL62This week
- CVE-2009-1122The WebDAV extension in Microsoft Internet Information Services (IIS) 5.0 on Windows 2000 SP4 does not properly decode URLs, which allows re60This week
- CVE-2005-4360The URL parser in Microsoft Internet Information Services (IIS) 5.1 on Windows XP Professional SP2 allows remote attackers to execute arbitr57Plan
- CVE-2008-1446Integer overflow in the Internet Printing Protocol (IPP) ISAPI extension in Microsoft Internet Information Services (IIS) 5.0 through 7.0 on50Plan
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
No fix version is recorded for this entry. Check the references for vendor advisories.
Exploit status
Weaponized
A ready exploit tool or active in-the-wild use is known for this vulnerability. This should be your top priority.
Evidence
- Metasploit module ×2
- Exploit-DB entry ×2
Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.
| Source | Kind | Date |
|---|---|---|
| Exploit-DB entry | remote | 2009-05-15 |
| Exploit-DB entry | remote | 2009-05-26 |
| Metasploit module | auxiliary/scanner/http/dir_webdav_unicode_bypassMS09-020 IIS6 WebDAV Unicode Auth Bypass Directory Scannerauxiliary | — |
| Metasploit module | auxiliary/scanner/http/ms09_020_webdav_unicode_bypassMS09-020 IIS6 WebDAV Unicode Authentication Bypassauxiliary | — |
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
- First PoC-26 d
- Published
- TodaySep 30, 2026+6321 d
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- P · data can be read
- Integrity
- P · data or configuration can be modified
- Availability
- P · the service can be disrupted
- Attack complexity
- Low
- Confidentiality impact
- P
- Integrity impact
- P
- Availability impact
- P
Weakness class (CWE)
CWE-287 · Improper AuthenticationCVSS vector
AV:N/AC:L/Au:N/C:P/I:P/A:P
nvd-primary
Root cause
Authentication is added route by route instead of being enforced in one place. When a route added later bypasses the shared middleware, the session check never runs for it.
The bug in code
The whole CWE-287 classA representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.
Vulnerable
app.use("/admin", requireSession, adminRouter);
// Route added later skips the middlewareapp.post("/admin-api/config", updateConfig);Fixed
const admin = express.Router();admin.use(requireSession, requireRole("admin"));
admin.post("/config", updateConfig);app.use("/admin", admin);Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
- Authentication AbuseCAPEC-114Medium
- Authentication BypassCAPEC-115Medium
- Identity SpoofingCAPEC-151likelihood: Medium · Medium
- Fake the Source of DataCAPEC-194Medium
- Exploiting Trust in ClientCAPEC-22likelihood: High · High
- Utilizing REST's Trust in the System Resource to Obtain Sensitive DataCAPEC-57likelihood: Medium · Very High
- Session HijackingCAPEC-593likelihood: High · Very High
- Token ImpersonationCAPEC-633Medium
ATT&CK techniques
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpChange log
No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.
References
- archives.neohapsis.com/archives/fulldisclosure/2009-05/0135.html
- archives.neohapsis.com/archives/fulldisclosure/2009-05/0139.html
- archives.neohapsis.com/archives/fulldisclosure/2009-05/0144.html
- archives.neohapsis.com/archives/fulldisclosure/2009-05/att-0135/IIS_Advisory.pdf
- blog.zoller.lu/2009/05/iis-6-webdac-auth-bypass-and-data.html
- isc.sans.org/diary.html?n&storyid=6397
- view.samurajdata.se/psview.php?id=023287d6&page=1
- www.attrition.org/pipermail/vim/2009-June/002192.html
- www.us-cert.gov/cas/techalerts/TA09-160A.html
- docs.microsoft.com/en-us/security-updates/securitybulletins/2009/ms09-020
- oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A6029
Vendor advisories and official records. Exploit/PoC links are deliberately left out.