CVE-2025-12642
HTTP Header Smuggling via Trailer Merge
Vexday Risk Score
13Low
SSVC decision (CISA)
Track
No exploitation signal → monitor
CVSS 6.9EPSS 0.3%KEV nãoPoC —Nuclei —Metasploit —Patch —
Lifecycle
03 Nov 2025Published on NVD
Recommendation: Monitor — no exploitation signal at the moment.
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
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N
Affected products
lighttpd · lighttpdWant to know if your infrastructure is exposed to this?
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