CVE-2000-0453

XFree86 3.3.x and 4.0 - Denial of Service via Malformed TCP Packet

Title source: llm
STIX 2.1

Exploitation Summary

EIP tracks 1 public exploit for CVE-2000-0453. PoCs published by Chris Evans.

AI-analyzed exploit summary This exploit demonstrates a denial-of-service (DoS) vulnerability in XFree86 by sending a malformed packet to the X server's TCP port 6000. The vulnerability arises from an integer underflow in the `AuthCheckSitePolicy()` function, causing the server to enter an infinite loop and consume 100% CPU.

Description

XFree86 3.3.x and 4.0 allows a user to cause a denial of service via a negative counter value in a malformed TCP packet that is sent to port 6000.

Exploits (1)

exploitdb WORKING POC VERIFIED
by Chris Evans · cdoslinux
https://www.exploit-db.com/exploits/19950

This exploit demonstrates a denial-of-service (DoS) vulnerability in XFree86 by sending a malformed packet to the X server's TCP port 6000. The vulnerability arises from an integer underflow in the `AuthCheckSitePolicy()` function, causing the server to enter an infinite loop and consume 100% CPU.

Classification
Working Poc 100%
Attack Type
Dos
Complexity
Trivial
Reliability
Reliable
Target: XFree86 3.3.5, 3.3.6, 4.0
No auth needed
Prerequisites: XFree86 server compiled with XCSECURITY defined · Access to TCP port 6000 on the target
devstral-2 · analyzed Feb 16, 2026 Full analysis →

References (3)

Core 3
Core References
Third Party Advisory mailing-list x_refsource_bugtraq
http://archives.neohapsis.com/archives/bugtraq/2000-05/0223.html
Third Party Advisory, VDB Entry vdb-entry x_refsource_bid
http://www.securityfocus.com/bid/1235
Various Sources vendor-advisory x_refsource_caldera
ftp://ftp.caldera.com/pub/security/OpenLinux/CSSA-2000-012.0.txt

Scores

EPSS 0.0296
EPSS Percentile 85.4%

Details

Status published
Products (3)
xfree86_project/x11r6 3.3.5
xfree86_project/x11r6 3.3.6
xfree86_project/x11r6 4.0
Published May 18, 2000
Tracked Since Feb 18, 2026