CVE-2025-12642
CriticalCVSS 9.1Exploitation Probability (EPSS)
Low risk29th percentile - higher than 29% of all known CVEs
Summary
lighttpd 1.4.80 incorrectly merges trailer fields into headers after HTTP request parsing. This behavior can be exploited to conduct HTTP Header Smuggling attacks. Successful exploitation may allow an attacker to bypass access control rules, inject unsafe input into backend logic that trusts request headers, and execute HTTP Request Smuggling attacks under some conditions.
Risk Assessment
An attacker could bypass access controls and inject malicious data into the backend, potentially leading to unauthorized access or code execution. This affects servers using lighttpd 1.4.80.
Recommendation
Update lighttpd to a version later than 1.4.80 (e.g., 1.4.81 or later). Until then, consider deploying WAF rules or limiting server exposure.
Other vulnerabilities in lighttpd
See all- CVE-2026-15701Critical
A vulnerability has been found in Totolink NR1800X firmware version 9.1.0u.6279_B20210910 in the Form_Logout function of the /formLogout.htm file within the lighttpd component. Manipulation of the Host argument causes a stack-based buffer overflow, which can be exploited remotely.
- CVE-2026-7546Critical
A security vulnerability has been detected in Totolink NR1800X version 9.1.0u.6279_B20210910 in the function find_host_ip of the lighttpd component. Manipulation of the Host argument leads to stack-based buffer overflow.
- CVE-2014-2323Critical
SQL injection vulnerability in mod_mysql_vhost.c in lighttpd before 1.4.35 allows remote attackers to execute arbitrary SQL commands via the host name, related to request_check_hostname.
Original NVD description (English source)
lighttpd1.4.80 incorrectly merged trailer fields into headers after http request parsing. This behavior can be exploited to conduct HTTP Header Smuggling attacks. Successful exploitation may allow an attacker to: * Bypass access control rules * Inject unsafe input into backend logic that trusts request headers * Execute HTTP Request Smuggling attacks under some conditions This issue affects lighttpd1.4.80
Vulnerability data from NVD (NIST) · CISA KEV · EPSS