CVE-1999-0821

FreeBSD seyon - Privilege Escalation

Title source: llm
STIX 2.1

Exploitation Summary

EIP tracks 2 public exploits for CVE-1999-0821. PoCs published by teleh0r, Brock Tellier.

AI-analyzed exploit summary This exploit targets a buffer overflow vulnerability in Seyon 2.1 rev. 4b on Linux. It uses a crafted buffer with NOP sleds and shellcode to execute '/bin/sh' via a return address override.

Description

FreeBSD seyon allows local users to gain privileges by providing a malicious program in the -emulator argument.

Exploits (2)

exploitdb WORKING POC VERIFIED
by teleh0r · perllocallinux
https://www.exploit-db.com/exploits/252

This exploit targets a buffer overflow vulnerability in Seyon 2.1 rev. 4b on Linux. It uses a crafted buffer with NOP sleds and shellcode to execute '/bin/sh' via a return address override.

Classification
Working Poc 95%
Attack Type
Rce
Complexity
Moderate
Reliability
Reliable
Target: Seyon 2.1 rev. 4b
No auth needed
Prerequisites: X server access · DISPLAY environment variable set
devstral-2 · analyzed Feb 16, 2026 Full analysis →
exploitdb WORKING POC VERIFIED
by Brock Tellier · textlocalfreebsd
https://www.exploit-db.com/exploits/19651

This exploit leverages the setgid dialer vulnerability in Seyon on FreeBSD 3.3-RELEASE to elevate privileges to the dialer group. It demonstrates a simple method to execute arbitrary code with elevated group permissions via the -emulator argument.

Classification
Working Poc 90%
Attack Type
Lpe
Complexity
Trivial
Reliability
Reliable
Target: Seyon on FreeBSD 3.3-RELEASE
No auth needed
Prerequisites: Local access to the target system · Seyon installed with setgid dialer
devstral-2 · analyzed Feb 16, 2026 Full analysis →

References (1)

Core 1
Core References
Third Party Advisory, VDB Entry vdb-entry x_refsource_bid
http://www.securityfocus.com/bid/838

Scores

EPSS 0.0077
EPSS Percentile 50.7%

Details

Status published
Products (1)
freebsd/freebsd 3.3
Published Nov 08, 1999
Tracked Since Feb 18, 2026