What is CVE-2009-1122?

CVE-2009-1122 is a vulnerability in Microsoft Internet Information Services, classified under Improper Authentication. Published 2009-06-10.

Is CVE-2009-1122 known to be exploited?

5 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Auth bypass in Microsoft Internet Information Services

CVE-2009-1122

The WebDAV extension in Microsoft Internet Information Services (IIS) 5.0 on Windows 2000 SP4 does not properly decode URLs, which allows remote attackers to bypass authentication, and possibly read or create files, via a crafted HTTP request, aka "IIS 5.0 WebDAV Authentication Bypass Vulnerability," a different vulnerability than CVE-2009-1535.

Vulnerability class: Broken Authentication

Published 2009-06-10 · last modified 2026-06-16.

CVSS v2 metric

CVSS v2 base score 7.5 (High). Vector: AV:N/AC:L/Au:N/C:P/I:P/A:P. This CVE predates CVSS v3 and has no v3 score from NVD.

EPSS exploit prediction

EPSS: 0.984 (99.9th percentile), scored 2026-10-16.

Very high probability of exploitation in the next 30 days — among the top 0.1% most-likely-to-be-exploited CVEs. 100th percentile — 99.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.984 · newest: 0.984 · change: 0.000

Affected products

Microsoft Internet Information Services — versions 5.0
Microsoft Windows 2000

Weakness classification (CWE)

CWE-287 — Improper Authentication

Public proof-of-concept exploits

References

oval.cisecurity.org/repository/search/definition/oval:org.mitre.oval:def:5861 (signature, Third Party Advisory, vdb-entry)
www.securitytracker.com/id (VDB Entry, Third Party Advisory, vdb-entry)
docs.microsoft.com/en-us/security-updates/securitybulletins/2009/ms09-020 (vendor-advisory, Patch, Vendor Advisory)
www.securityfocus.com/bid/35232 (VDB Entry, Third Party Advisory, vdb-entry)
www.us-cert.gov/cas/techalerts/TA09-160A.html (US Government Resource, Third Party Advisory, third-party-advisory)
www.vupen.com/english/advisories/2009/1539 (Third Party Advisory, vdb-entry)
www.attrition.org/pipermail/vim/2009-June/002192.html (mailing-list, Third Party Advisory)

Frequently asked questions

What is CVE-2009-1122?: CVE-2009-1122 is a vulnerability in Microsoft Internet Information Services, classified under Improper Authentication. Published 2009-06-10.
Is CVE-2009-1122 known to be exploited?: 5 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.