Servers and applications
CVE-2009-4444
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…
- Severity
- Medium 6.0
- Published
- 29 Dec 2009
- Last changed
- 16 Jun 2026
- Added to UpHeron
- 21 Oct 2026
- Exploit chance
- 64% in the next 30 daysHigher than 99% of CVEs. EPSS by FIRST, 12 Nov 2026
- Attack
- Over the network · Needs a login
- Attacker can
- Read some data · Change some data · Slow it down
- CVSS vector
AV:N/AC:M/Au:S/C:P/I:P/A:P- Sources
- NVD
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 software
| Software | Affected versions |
|---|---|
Microsoft IISServers and applications · cpe:a:microsoft:internet_information_services |
|