// For flags

CVE-2013-6890

DenyHosts - 'regex.py' Remote Denial of Service

Severity Score

7.5
*CVSS v3

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

1
*Multiple Sources

Exploited in Wild

-
*KEV

Decision

-
*SSVC
Descriptions

denyhosts 2.6 uses an incorrect regular expression when analyzing authentication logs, which allows remote attackers to cause a denial of service (incorrect block of IP addresses) via crafted login names.

denyhosts v2.6 utiliza una expresión regular incorrecta al analizar los registros de autenticación, , lo cual permite a atacantes remotos causar una denegación de servicio (secuencia incorrecta de direcciones IP) a través de nombres de inicio de sesión manipulados.

Helmut Grohne discovered that denyhosts, a tool preventing SSH brute-force attacks, could be used to perform remote denial of service against the SSH daemon. Incorrectly specified regular expressions used to detect brute force attacks in authentication logs could be exploited by a malicious user to forge crafted login names in order to make denyhosts ban arbitrary IP addresses.

*Credits: N/A
CVSS Scores
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High
Attack Vector
Network
Attack Complexity
Low
Authentication
None
Confidentiality
None
Integrity
None
Availability
Partial
* Common Vulnerability Scoring System
SSVC
  • Decision:-
Exploitation
-
Automatable
-
Tech. Impact
-
* Organization's Worst-case Scenario
Timeline
  • 2013-11-28 CVE Reserved
  • 2013-12-19 First Exploit
  • 2013-12-23 CVE Published
  • 2024-08-06 CVE Updated
  • 2025-03-30 EPSS Updated
  • ---------- Exploited in Wild
  • ---------- KEV Due Date
CWE
  • CWE-287: Improper Authentication
CAPEC
Affected Vendors, Products, and Versions
Vendor Product Version Other Status
Vendor Product Version Other Status <-- --> Vendor Product Version Other Status
Debian
Search vendor "Debian"
 Debian Linux
Search vendor "Debian" for product "Debian Linux"
 6.0
Search vendor "Debian" for product "Debian Linux" and version "6.0"
-
Affected
Debian
Search vendor "Debian"
 Debian Linux
Search vendor "Debian" for product "Debian Linux"
 7.0
Search vendor "Debian" for product "Debian Linux" and version "7.0"
-
Affected
Debian
Search vendor "Debian"
 Debian Linux
Search vendor "Debian" for product "Debian Linux"
 7.1
Search vendor "Debian" for product "Debian Linux" and version "7.1"
-
Affected
Fedoraproject
Search vendor "Fedoraproject"
 Fedora
Search vendor "Fedoraproject" for product "Fedora"
*-
Affected
Phil Schwartz
Search vendor "Phil Schwartz"
 Denyhosts
Search vendor "Phil Schwartz" for product "Denyhosts"
 2.6
Search vendor "Phil Schwartz" for product "Denyhosts" and version "2.6"
-
Affected