CVE-2009-4491: acme thttpd Improper Input Validation
Vulnerability summary
CVE-2009-4491 is a critical (CVSS 9.8) Improper Input Validation vulnerability in acme thttpd. EPSS estimates a 13.72% chance of exploitation in the next 30 days, higher than 96.4% of scored vulnerabilities. 2 public exploits are recorded.
Timeline
- 13-01-2010PublishedVulnerability first disclosed.
- 07-08-2024Last modifiedVulnerability information updated.
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.
CVSS metrics
3 scores · 2 sources · 2 versions- NVDNIST9.8CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS trend
Probability
13.72%
Chance of exploitation in the next 30 days
Percentile
96%
Versus all other CVEs
30-day change
0.00 pp
From 13.72% on 20-09-2026
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
2 foundExploit Reference (ush.it)
Maturity: unknown
thttpd 2.24 - HTTP Request Escape Sequence Terminal Command Injection
Maturity: weaponized
Weaknesses
CWE · root cause- CWE-20Improper Input ValidationThe product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
- CWE-94Improper Control of Generation of Code ('Code Injection')The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.
Affected systems
Acme1 product
- thttpd2.25:b
1 vendor · 1 product
References
4 links- seclists.org/fulldisclosure/2023/Nov/13Mailing List