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Lotus Domino vulnerable to DoS via crafted HTTP header requests

Vulnerability Note VU#601312

Original Release Date: 2001-07-12 | Last Revised: 2001-07-17


The Lotus Domino Web Server contains a flaw that could be exploited to cause a denial of service.


HTTP requests with uniquely crafted headers using "Accept", "Accept-Charset", "Accept-Encoding", "Accept-Language" or "Content-Type" are not freed properly. This means that submitting numerous requests for a document, such as root (/), with various accept fields (accept: a, accept: aa, accept: aaa, ...) will cause the server to run out of physical memory. The server will then display an error message similar to this one:

"HTTP Server: Could allocate 8036 bytes of memoryOut of memory in HTMemPoolAlloc (file htmpool.c, line 506).Program aborted."

One of two things will then happen:

1) Processes that required working threads such as Task Manager will cease to function and the Lotus Server, while continuing to run, will no longer answer requests on TCP port 80. Also, any occupied memory will not be released.


2) The Lotus Server process will crash, and will need to be restarted in order to regain functionality. The rest of the services, unrelated to the Lotus Server, on the host will continue to function normally.


The server will eventually run out of physical memory and a denial of service will result.


Upgrade to Notes/Domino 5.0.7 or later. See

An application layer filter may be able to detect and block unapproved requests.

Vendor Information


Lotus Affected

Notified:  October 16, 2000 Updated: July 12, 2001



Vendor Statement

[We] have addressed the issues reported to us by Defcom in R5.0.7

Vendor Information

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


See also

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Our thanks to Defcom Labs, which published an advisory on this and other problems, available at

This document was written by Jason Rafail and is based on information obtained from a Defcom Labs Advisory.

Other Information

CVE IDs: None
Severity Metric: 9.98
Date Public: 2001-04-11
Date First Published: 2001-07-12
Date Last Updated: 2001-07-17 19:15 UTC
Document Revision: 19

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