CVE-2025-12642
Critical
Description
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
SeverityCritical
CVSS9.1
Exploit probability—
Product
Lighttpd
PublishedNov 3, 2025
First seenNov 3, 2025
Weakness typeCWE-444CWE-444
How to fix
Sources list no fixed version or patch link for this vulnerability.
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| lighttpd lighttpd | 1.4.80 | — |
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