# CVE-2009-1535: Auth bypass in n/a

> Remote attackers can bypass WebDAV authentication in IIS to read, create, or modify protected files via crafted Unicode characters in the URI.

- **Severity:** High 7.5 (`AV:N/AC:L/Au:N/C:P/I:P/A:P`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 10 Jun 2009
- **Updated:** 7 Aug 2024
- **Also known as:** CVE-2009-1676, GHSA-f2c7-qmx6-wq66

## What is CVE-2009-1535?

CVE-2009-1535 is a high-severity authentication bypass vulnerability in Microsoft Internet Information Services, published on 10 Jun 2009. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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.

Weakness: CWE-287 (Improper Authentication)

## Which versions are affected by CVE-2009-1535?

It affects 1 product.


Products: Microsoft Internet Information Services.

## How do I fix CVE-2009-1535?

No fix has been published for CVE-2009-1535 yet. Limit exposure of the affected software until one is available.

## Is CVE-2009-1535 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2009-1535 exists.

Public exploit code:

- Microsoft IIS 6.0 - WebDAV Remote Authentication Bypass (1) (exploitdb)
- Microsoft IIS 6.0 - WebDAV Remote Authentication Bypass (2) (exploitdb)
- MS09-020 IIS6 WebDAV Unicode Auth Bypass Directory Scanner (metasploit)
- MS09-020 IIS6 WebDAV Unicode Authentication Bypass (metasploit)

## Other vulnerabilities in Microsoft Internet Information Services

- [CVE-2017-7269](https://insights.sbomify.com/CVE-2017-7269/): Microsoft Windows Server Buffer Overflow (critical 9.8, exploited in the wild)
- [CVE-2010-3972](https://insights.sbomify.com/CVE-2010-3972/): Memory corruption in n/a (critical 10.0)
- [CVE-2008-4301](https://insights.sbomify.com/CVE-2008-4301/): Other in n/a (critical 10.0)
- [CVE-2007-2815](https://insights.sbomify.com/CVE-2007-2815/): The "hit-highlighting" functionality in webhits.dll in Microsoft Internet Information Services (IIS) Web Server 5.0 only uses Windows NT ACL (critical 10.0)
- [CVE-2003-0224](https://insights.sbomify.com/CVE-2003-0224/): Buffer overflow in ssinc.dll for Microsoft Internet Information Services (IIS) 5.0 allows local users to execute arbitrary code via a web pa (critical 10.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2009-1535 and fix it if it is affected.

What it is: CVE-2009-1535 is a high-severity authentication bypass vulnerability in Microsoft Internet Information Services, published on 10 Jun 2009. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2009-1535 exists.

Affected product: Microsoft Internet Information Services. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2009-1535/ (Markdown: https://insights.sbomify.com/CVE-2009-1535/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2009-1535
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2009-1535
- OSV: https://osv.dev/vulnerability/CVE-2009-1535

---
From sbomify Insights: https://insights.sbomify.com/CVE-2009-1535/
Summaries are generated and may contain mistakes; the official description above is the record.