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No exploitation reportedFix available

CVE-2025-12642

No exploitation reported by the sources we read.

  • Published2025-11-03
  • WeaknessCWE-444

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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

Timeline

dates in UTC
  1. 2025-11-0320:17CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-11-03 21:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2025-12642?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2025-12642?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD
lighttpd
BranchAffectedFixed in
1.4= 1.4.80no fix published

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Products declared by the CNA1 product

As Toreon, the CNA that assigned this CVE, declared them in the CVE record; versions as written.

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2025-11-03

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • lighttpdUbuntu:Pro:18.04:LTSall versions · no fixed version listed
  • lighttpdUbuntu:Pro:16.04:LTSall versions · no fixed version listed
  • lighttpdUbuntu:Pro:14.04:LTSall versions · no fixed version listed
  • lighttpdUbuntu:26.10all versions · no fixed version listed
  • lighttpdUbuntu:26.04:LTSall versions · no fixed version listed
  • lighttpdUbuntu:25.10all versions · no fixed version listed
  • lighttpdUbuntu:24.04:LTSall versions · no fixed version listed
  • lighttpdUbuntu:22.04:LTSall versions · no fixed version listed

1 more package range on OSV.dev

Full record on NVD

Fix

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
none listed
PoC-in-GitHub
Metasploit modules
none listed
Metasploit Framework

Sources

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
CVSS 4.0 vector
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Published
2025-11-03
Last Modified
2026-10-19
NVD status
Analyzed
GitHub Advisory
GHSA-fvx8-q97q-cw73

Frequently asked questions

What is CVE-2025-12642?

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

Is CVE-2025-12642 actively exploited?

Active exploitation of CVE-2025-12642 has not been confirmed. Its EPSS score was 0.4% on 2026-11-03, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2025-12642?

CVE-2025-12642 has a CVSS v3 base score of 9.1 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.

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