Is CVE-2025-12642 actively exploited?

No active exploitation of CVE-2025-12642 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2025-12642 be exploited remotely?

Yes. CVE-2025-12642 is exploitable remotely over the network (CVSS attack vector: Network).

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

CVE-2025-12642 has a CVSS score of 9.1 (CRITICAL).

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CRITICAL

CVE-2025-12642

CWE-444Published: November 3, 2025· Updated: Jun 17, 2026

9.1

CVSS v3.1

Official 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

NVD Source

Risk Analysis

This critical vulnerability in lighttpd version 1.4.80 allows for HTTP Header Smuggling attacks due to incorrect merging of trailer fields into headers. With a CVSS score of 9.1, successful exploitation could lead to bypassing access control, injecting unsafe input into backend logic, and executing HTTP Request Smuggling attacks. The absence of an EPSS score means the exploitation likelihood is not yet assessed, but the high CVSS score highlights its severity.

No public exploit is currently known for this vulnerability. However, its remote exploitability (AV:N) and low attack complexity (AC:L) make it a significant concern.

Recommended Action

To mitigate this vulnerability, upgrade lighttpd to a version beyond 1.4.80. Implement robust input validation and ensure proper handling of HTTP headers in your web server configuration.

Generated by the CTIWATCH analysis pipeline from this CVE's metadata (CVSS, EPSS, KEV status, exploit intelligence). Verify against vendor advisories before acting.

Technical Analysis

CVE-2025-12642 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), with a CVSS base score of 9.1.