What’s Vulnerable › Vulnerabilities

CVE-2009-4444

• Severity: medium (CVSS 6.0 v2.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 63.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2009-12-29 · updated 2026-06-16

Description

Microsoft Internet Information Services (IIS) 5.x and 6.x uses only the portion of a filename before a ; (semicolon) character to determine the file extension, which allows remote attackers to bypass intended extension restrictions of third-party upload applications via a filename with a (1) .asp, (2) .cer, or (3) .asa first extension, followed by a semicolon and a safe extension, as demonstrated by the use of asp.dll to handle a .asp;.jpg file.

Affected products

• Microsoft IIS: 5.0, 6.0

References

• http://blogs.technet.com/msrc/archive/2009/12/27/new-reports-of-a-vulnerability-in-iis.aspx
• http://secunia.com/advisories/37831
• http://securitytracker.com/id?1023387
• http://soroush.secproject.com/downloadable/iis-semicolon-report.pdf
• http://www.securityfocus.com/bid/37460
• http://www.vupen.com/english/advisories/2009/3634
• http://blogs.technet.com/msrc/archive/2009/12/27/new-reports-of-a-vulnerability-in-iis.aspx
• http://secunia.com/advisories/37831
• http://securitytracker.com/id?1023387
• http://soroush.secproject.com/downloadable/iis-semicolon-report.pdf
• http://www.securityfocus.com/bid/37460
• http://www.vupen.com/english/advisories/2009/3634

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