Critical severity · published Feb 9, 2026
CVE-2026-22903
Stack Overflow via SESSIONID Cookie in lighttpd
9.8
CVSS
0.8%
EPSS
No
On KEV
Description
An unauthenticated remote attacker can send a crafted HTTP request containing an overly long SESSIONID cookie. This can trigger a stack buffer overflow in the modified lighttpd server, causing it to crash and potentially enabling remote code execution due to missing stack protections.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.8% · higher than 55% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
08
0852-1322 · WAGO
0.0.0 through 2.64; 2.64 · source: vendor
08
0852-1328 · WAGO
0.0.0 through 2.64; 2.64 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-22903
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-22903
certvde.com
https://certvde.com/de/advisories/VDE-2026-004
More from 0852-1322
9.8
CVE-2026-22906
Hardcoded Key Allows Credential Disclosure
9.8
CVE-2026-22904
Stack Overflow via Oversized Cookie Fields in lighttpd
7.5
CVE-2026-22905
Authentication Bypass via URI Traversal