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🛡️ CVE-2025-12642 — lighttpd

🔴 CVSS 9.1 — Critical ✅ No Known Exploit CWE-444 NVD
9.1
CVSS Score
0 Low4 Medium7 High9 Critical10

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

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality high, integrity high, availability none.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

  • Attack vector: Network — reachable from anywhere that can route to the service.
  • Attack complexity: Low — the attack works reliably, with no preparation.
  • Privileges required: None — an unauthenticated stranger can try it.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Unchanged — the damage stays inside the vulnerable component.
  • Confidentiality impact: High — total loss, or loss the attacker controls.
  • Integrity impact: High — total loss, or loss the attacker controls.
  • Availability impact: None.

Weakness class

CVE-2025-12642 is classified as CWE-444: HTTP Request Smuggling. A proxy and a server disagree on where one request ends, letting an attacker slip a second request past the front end.

Affected software

CVE-2025-12642 is recorded against 1 package.

  • lighttpd

Timeline and source

Published on 3 November 2025 and last revised on 17 June 2026. No public exploit is currently recorded for this entry. A vendor advisory or fix has been published. Record sourced from NVD.

References

github.com

Other advisories for this package

lighttpd has other advisories on record. If you are patching this one, these are worth checking on the same host:

Same weakness in other software

These advisories are the same class of weakness (CWE-444: HTTP Request Smuggling) in other software:

CVE-2025-12642 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity CRITICAL
CVSS Score 9.1
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
CWE CWE-444
Public Exploit ✅ No
Source NVD
Published 2025-11-03
Updated 2026-08-20
Modified 2026-06-17

Affected Packages

Software From version Fixed in
lighttpd — —

Exploit Protection

Are you running lighttpd?

CVE-2025-12642 carries CVSS 9.1 Critical rating. BotEraser checks your installation against this and other known CVE records, and blocks IPs associated with exploit activity.

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ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.

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