Chunked encoding post can consume excessive memory on IIS 4.0 webserver

ID VU:25716
Type cert
Reporter CERT
Modified 2002-06-13T18:42:00



Microsoft IIS 4.0, circa March 2000, contained a vulnerability that allowed an intruder to consume unlimited memory on a vulnerable server.


Older versions of IIS 4.0, circa March 2000, contained a vulnerability in the chunked-encoding transfer mechanism that permitted an intruder to allocate unlimited memory on the server. Quoting from Microsoft security bulletin MS00-018:

_IIS 4.0 supports chunked encoding transfers, but does not limit the size of the buffer that can be reserved. This would allow a malicious user to request an extremely large buffer for a POST or PUT operation, but never actually send data, thereby blocking memory on the server that had been allocated to the session. _

This would not permit an intruder to execute code.


Intruders can interrupt the ordinary operation of a vulnerable IIS 4.0 server, potentially preventing it from responding to legitimate requests. Additionally, an intruder may be able to degrade the overall performance of other process on the machine.


Apply a patch as described in MS00-018.

Vendor Information


Filter by status: All Affected Not Affected Unknown

Filter by content: __ Additional information available

__ Sort by: Status Alphabetical

Expand all

Javascript is disabled. Click here to view vendors.

Microsoft Corporation __ Affected

Updated: June 13, 2002



Vendor Statement

See <>

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.


The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

CVSS Metrics

Group | Score | Vector
Base | |
Temporal | |
Environmental | |


  • <>
  • <>
  • <>
  • <>
  • <>


Thanks to Petteri Stenius for reporting this vulnerability.

This document was written by Shawn V Hernan based on information provided by Microsoft in MS00-018.

Other Information

CVE IDs: | CVE-2000-0226
Severity Metric: | 2.62
Date Public: | 2000-03-20
Date First Published: | 2002-06-13
Date Last Updated: | 2002-06-13 18:42 UTC
Document Revision: | 3