CVE-2013-4434

Dropbear SSH Server before 2013.59 generates error messages for a failed logon attempt with different time delays depending on whether the user account exists, which allows remote attackers to discover valid usernames.

Published: 2013-10-25 Last update: 2026-04-29 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2013-4434 is rated Moderate Risk (56.1/100): CVSS Medium severity, with high exploitation likelihood (EPSS 5.75%, 92th percentile). EPSS ranks this CVE among the most likely to be exploited in the near term. EPSS rose +3.84% over the last day, indicating growing attacker interest. High exploitation likelihood—assess exposure and prioritize remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2013-4434

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 1.91% 5.75% +3.84%
2 2026-03-04 2.17% 1.91% -0.26%
3 2026-03-01 — 2.17% —

Full EPSS history (44 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2013-4434

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.0 2.0 MEDIUM
AV:N/AC:L/Au:N/C:P/I:N/A:N Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:N)
No availability impact.
 10.0 2.9 [email protected]

Weakness enumeration for CVE-2013-4434

OS Trackers for CVE-2013-4434

vendor priority summary link
debian low CVE-2013-4434 low priority: Debian including 1 source packages (dropbear), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2013-4434
ubuntu medium CVE-2013-4434 medium priority: Ubuntu including 1 source packages (dropbear), 13 status rows across 13 suites (lucid, precise, quantal, raring, saucy, trusty, upstream, utopic, vivid, wily, xenial, yakkety, zesty): not-affected 6, ignored 5, DNE 1, released 1. https://ubuntu.com/security/CVE-2013-4434

Affected software / configurations for CVE-2013-4434

Vendor Product Version Raw CPE
dropbear_ssh_project dropbear_ssh < 2013.59 cpe:2.3:a:dropbear_ssh_project:dropbear_ssh:*:*:*:*:*:*:*:*

References for CVE-2013-4434

cvelogic Threat Intelligence