Is CVE-2009-4491 actively exploited?

A proof-of-concept exploit is publicly available for CVE-2009-4491, but active exploitation has not been confirmed.

Can CVE-2009-4491 be exploited remotely?

Yes. CVE-2009-4491 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2009-4491?

CVE-2009-4491 has a CVSS score of 9.8 (CRITICAL).

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CRITICALPOC

CVE-2009-4491

CWE-20Published: January 13, 2010· Updated: Jun 16, 2026

9.8

CVSS v3.1

Official Description

thttpd 2.25b0 writes data to a log file without sanitizing non-printable characters, which might allow remote attackers to modify a window's title, or possibly execute arbitrary commands or overwrite files, via an HTTP request containing an escape sequence for a terminal emulator.

NVD Source

Technical Analysis

CVE-2009-4491 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), availability disruption (denial of service), with a CVSS base score of 9.8.

A proof-of-concept (PoC) exploit exists for CVE-2009-4491. While not yet confirmed in active campaigns, the availability of PoC code increases exploitation risk substantially.