CVE-2026-22904CWE-121

Stack Overflow via Oversized Cookie Fields in lighttpd

Critical · published February 9, 2026

CVSS v3.1
9.8
EPSS
1%
Percentile
49.5
In the wild
Unconfirmed
What it is

🔥 An oversized cookie could bring your system to its knees! An attacker can send massive cookie values that trigger a stack buffer overflow. 🚨 Think of it like a restaurant trying to accommodate way too many reservations at once — if everyone showed up with extra-large orders, the kitchen would be overwhelmed and unable to serve anyone! This vulnerability allows an unauthenticated attacker to flood your server with oversized cookie values, leading to a denial-of-service situation where legitimate users can't access services. In the worst case, it opens the door for remote code execution, allowing malicious actions that could devastate your system.

Put simply

Think of it like a restaurant trying to accommodate way too many reservations at once — if everyone showed up with extra-large orders, the kitchen would be overwhelmed and unable to serve anyone! The flaw arises from improper length handling when parsing multiple cookie fields, particularly the TRACKID field. This oversight permits attackers to exploit stack buffer overflows, destabilizing the application.

What to do

This vulnerability allows an unauthenticated attacker to flood your server with oversized cookie values, leading to a denial-of-service situation where legitimate users can't access services. In the worst case, it opens the door for remote code execution, allowing malicious actions that could devastate your system. Update your web server software to the latest version that addresses this vulnerability immediately. Implement strict controls on cookie value lengths to mitigate the risk of oversized entries. Regularly audit your application for similar vulnerabilities to ensure continued security! You've got this! Follow these steps to safeguard your system and keep those oversized cookies at bay! 🛡️

The record
Technical detail
CVSS v3.1
9.8 · CRITICAL
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS v4.0
Not supplied
EPSS
0.00629 · 49.5th percentile
Weakness
CWE-121 · Stack-based Buffer Overflow
Published
2026-02-09T07:40Z
EPSS history
Timeline
  • 09 FEB 07:40Z
    Stack Overflow via Oversized Cookie Fields in lighttpd
    cvelistv5