CVE-2011-4096

The idnsGrokReply function in Squid before 3.1.16 does not properly free memory, which allows remote attackers to cause a denial of service (daemon abort) via a DNS reply containing a CNAME record that references another CNAME record that contains an empty A record.

Published: 2011-11-17 Last update: 2026-04-29 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2011-4096 is rated Moderate Risk (52.8/100): CVSS Medium severity, with high exploitation likelihood (EPSS 62.49%, 98th percentile). EPSS ranks this CVE among the most likely to be exploited in the near term. 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-2011-4096

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 2025-12-28 64.04% 62.49% -1.55%
2 2025-12-27 62.49% 64.04% +1.55%
3 2025-10-28 — 62.49% —

Full EPSS history (15 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2011-4096

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:N/I:N/A:P 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:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 2.9 [email protected]

Weakness enumeration for CVE-2011-4096

OS Trackers for CVE-2011-4096

vendor priority summary link
gentoo normal CVE-2011-4096: 1 GLSA(s) (201309-22), 1 atom(s) (net-proxy/squid); latest impact normal. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2011-4096
redhat medium — https://access.redhat.com/security/cve/CVE-2011-4096
ubuntu medium CVE-2011-4096 medium priority: Ubuntu including 1 source packages (squid3), 6 status rows across 6 suites (hardy, lucid, maverick, natty, oneiric, upstream): released 4, not-affected 2. https://ubuntu.com/security/CVE-2011-4096

Affected software / configurations for CVE-2011-4096

Vendor Product Version Raw CPE
squid-cache squid <= 3.1.15 cpe:2.3:a:squid-cache:squid:*:*:*:*:*:*:*:*
squid-cache squid 3.0 cpe:2.3:a:squid-cache:squid:3.0:*:*:*:*:*:*:*
squid-cache squid 3.0 cpe:2.3:a:squid-cache:squid:3.0:*:pre1:*:*:*:*:*
squid-cache squid 3.0 cpe:2.3:a:squid-cache:squid:3.0:*:pre2:*:*:*:*:*
squid-cache squid 3.0 cpe:2.3:a:squid-cache:squid:3.0:*:pre3:*:*:*:*:*
squid-cache squid 3.0 cpe:2.3:a:squid-cache:squid:3.0:*:pre4:*:*:*:*:*
squid-cache squid 3.0 cpe:2.3:a:squid-cache:squid:3.0:*:pre5:*:*:*:*:*
squid-cache squid 3.0 cpe:2.3:a:squid-cache:squid:3.0:*:pre6:*:*:*:*:*
squid-cache squid 3.0 cpe:2.3:a:squid-cache:squid:3.0:*:pre7:*:*:*:*:*
squid-cache squid 3.0 cpe:2.3:a:squid-cache:squid:3.0:*:stable1:*:*:*:*:*
squid-cache squid 3.0 cpe:2.3:a:squid-cache:squid:3.0:*:stable10:*:*:*:*:*
squid-cache squid 3.0 cpe:2.3:a:squid-cache:squid:3.0:*:stable11:*:*:*:*:*
squid-cache squid 3.0 cpe:2.3:a:squid-cache:squid:3.0:*:stable12:*:*:*:*:*
squid-cache squid 3.0 cpe:2.3:a:squid-cache:squid:3.0:*:stable13:*:*:*:*:*
squid-cache squid 3.0 cpe:2.3:a:squid-cache:squid:3.0:*:stable14:*:*:*:*:*
squid-cache squid 3.0 cpe:2.3:a:squid-cache:squid:3.0:*:stable15:*:*:*:*:*
squid-cache squid 3.0 cpe:2.3:a:squid-cache:squid:3.0:*:stable2:*:*:*:*:*
squid-cache squid 3.0 cpe:2.3:a:squid-cache:squid:3.0:*:stable3:*:*:*:*:*
squid-cache squid 3.0 cpe:2.3:a:squid-cache:squid:3.0:*:stable4:*:*:*:*:*
squid-cache squid 3.0 cpe:2.3:a:squid-cache:squid:3.0:*:stable5:*:*:*:*:*
squid-cache squid 3.0 cpe:2.3:a:squid-cache:squid:3.0:*:stable6:*:*:*:*:*
squid-cache squid 3.0 cpe:2.3:a:squid-cache:squid:3.0:*:stable7:*:*:*:*:*
squid-cache squid 3.0 cpe:2.3:a:squid-cache:squid:3.0:*:stable8:*:*:*:*:*
squid-cache squid 3.0 cpe:2.3:a:squid-cache:squid:3.0:*:stable9:*:*:*:*:*
squid-cache squid 3.0 cpe:2.3:a:squid-cache:squid:3.0:rc1:stable11:*:*:*:*:*
squid-cache squid 3.0 cpe:2.3:a:squid-cache:squid:3.0:rc4:*:*:*:*:*:*
squid-cache squid 3.0.stable1 cpe:2.3:a:squid-cache:squid:3.0.stable1:*:*:*:*:*:*:*
squid-cache squid 3.0.stable2 cpe:2.3:a:squid-cache:squid:3.0.stable2:*:*:*:*:*:*:*
squid-cache squid 3.0.stable3 cpe:2.3:a:squid-cache:squid:3.0.stable3:*:*:*:*:*:*:*
squid-cache squid 3.0.stable4 cpe:2.3:a:squid-cache:squid:3.0.stable4:*:*:*:*:*:*:*
squid-cache squid 3.0.stable5 cpe:2.3:a:squid-cache:squid:3.0.stable5:*:*:*:*:*:*:*
squid-cache squid 3.0.stable6 cpe:2.3:a:squid-cache:squid:3.0.stable6:*:*:*:*:*:*:*
squid-cache squid 3.0.stable7 cpe:2.3:a:squid-cache:squid:3.0.stable7:*:*:*:*:*:*:*
squid-cache squid 3.0.stable8 cpe:2.3:a:squid-cache:squid:3.0.stable8:*:*:*:*:*:*:*
squid-cache squid 3.0.stable9 cpe:2.3:a:squid-cache:squid:3.0.stable9:*:*:*:*:*:*:*
squid-cache squid 3.0.stable10 cpe:2.3:a:squid-cache:squid:3.0.stable10:*:*:*:*:*:*:*
squid-cache squid 3.0.stable11 cpe:2.3:a:squid-cache:squid:3.0.stable11:*:*:*:*:*:*:*
squid-cache squid 3.0.stable11 cpe:2.3:a:squid-cache:squid:3.0.stable11:rc1:*:*:*:*:*:*
squid-cache squid 3.0.stable12 cpe:2.3:a:squid-cache:squid:3.0.stable12:*:*:*:*:*:*:*
squid-cache squid 3.0.stable13 cpe:2.3:a:squid-cache:squid:3.0.stable13:*:*:*:*:*:*:*
squid-cache squid 3.0.stable14 cpe:2.3:a:squid-cache:squid:3.0.stable14:*:*:*:*:*:*:*
squid-cache squid 3.0.stable15 cpe:2.3:a:squid-cache:squid:3.0.stable15:*:*:*:*:*:*:*
squid-cache squid 3.0.stable16 cpe:2.3:a:squid-cache:squid:3.0.stable16:*:*:*:*:*:*:*
squid-cache squid 3.0.stable16 cpe:2.3:a:squid-cache:squid:3.0.stable16:rc1:*:*:*:*:*:*
squid-cache squid 3.0.stable17 cpe:2.3:a:squid-cache:squid:3.0.stable17:*:*:*:*:*:*:*
squid-cache squid 3.0.stable18 cpe:2.3:a:squid-cache:squid:3.0.stable18:*:*:*:*:*:*:*
squid-cache squid 3.0.stable19 cpe:2.3:a:squid-cache:squid:3.0.stable19:*:*:*:*:*:*:*
squid-cache squid 3.0.stable20 cpe:2.3:a:squid-cache:squid:3.0.stable20:*:*:*:*:*:*:*
squid-cache squid 3.0.stable21 cpe:2.3:a:squid-cache:squid:3.0.stable21:*:*:*:*:*:*:*
squid-cache squid 3.0.stable22 cpe:2.3:a:squid-cache:squid:3.0.stable22:*:*:*:*:*:*:*
squid-cache squid 3.0.stable23 cpe:2.3:a:squid-cache:squid:3.0.stable23:*:*:*:*:*:*:*
squid-cache squid 3.0.stable24 cpe:2.3:a:squid-cache:squid:3.0.stable24:*:*:*:*:*:*:*
squid-cache squid 3.0.stable25 cpe:2.3:a:squid-cache:squid:3.0.stable25:*:*:*:*:*:*:*
squid-cache squid 3.1 cpe:2.3:a:squid-cache:squid:3.1:*:*:*:*:*:*:*
squid-cache squid 3.1.0.1 cpe:2.3:a:squid-cache:squid:3.1.0.1:*:*:*:*:*:*:*
squid-cache squid 3.1.0.2 cpe:2.3:a:squid-cache:squid:3.1.0.2:*:*:*:*:*:*:*
squid-cache squid 3.1.0.3 cpe:2.3:a:squid-cache:squid:3.1.0.3:*:*:*:*:*:*:*
squid-cache squid 3.1.0.4 cpe:2.3:a:squid-cache:squid:3.1.0.4:*:*:*:*:*:*:*
squid-cache squid 3.1.0.5 cpe:2.3:a:squid-cache:squid:3.1.0.5:*:*:*:*:*:*:*
squid-cache squid 3.1.0.6 cpe:2.3:a:squid-cache:squid:3.1.0.6:*:*:*:*:*:*:*
squid-cache squid 3.1.0.7 cpe:2.3:a:squid-cache:squid:3.1.0.7:*:*:*:*:*:*:*
squid-cache squid 3.1.0.8 cpe:2.3:a:squid-cache:squid:3.1.0.8:*:*:*:*:*:*:*
squid-cache squid 3.1.0.9 cpe:2.3:a:squid-cache:squid:3.1.0.9:*:*:*:*:*:*:*
squid-cache squid 3.1.0.10 cpe:2.3:a:squid-cache:squid:3.1.0.10:*:*:*:*:*:*:*
squid-cache squid 3.1.0.11 cpe:2.3:a:squid-cache:squid:3.1.0.11:*:*:*:*:*:*:*
squid-cache squid 3.1.0.12 cpe:2.3:a:squid-cache:squid:3.1.0.12:*:*:*:*:*:*:*
squid-cache squid 3.1.0.13 cpe:2.3:a:squid-cache:squid:3.1.0.13:*:*:*:*:*:*:*
squid-cache squid 3.1.0.14 cpe:2.3:a:squid-cache:squid:3.1.0.14:*:*:*:*:*:*:*
squid-cache squid 3.1.0.15 cpe:2.3:a:squid-cache:squid:3.1.0.15:*:*:*:*:*:*:*
squid-cache squid 3.1.0.16 cpe:2.3:a:squid-cache:squid:3.1.0.16:*:*:*:*:*:*:*
squid-cache squid 3.1.0.17 cpe:2.3:a:squid-cache:squid:3.1.0.17:*:*:*:*:*:*:*
squid-cache squid 3.1.0.18 cpe:2.3:a:squid-cache:squid:3.1.0.18:*:*:*:*:*:*:*
squid-cache squid 3.1.1 cpe:2.3:a:squid-cache:squid:3.1.1:*:*:*:*:*:*:*
squid-cache squid 3.1.2 cpe:2.3:a:squid-cache:squid:3.1.2:*:*:*:*:*:*:*
squid-cache squid 3.1.3 cpe:2.3:a:squid-cache:squid:3.1.3:*:*:*:*:*:*:*
squid-cache squid 3.1.4 cpe:2.3:a:squid-cache:squid:3.1.4:*:*:*:*:*:*:*
squid-cache squid 3.1.5 cpe:2.3:a:squid-cache:squid:3.1.5:*:*:*:*:*:*:*
squid-cache squid 3.1.5.1 cpe:2.3:a:squid-cache:squid:3.1.5.1:*:*:*:*:*:*:*
squid-cache squid 3.1.6 cpe:2.3:a:squid-cache:squid:3.1.6:*:*:*:*:*:*:*
squid-cache squid 3.1.7 cpe:2.3:a:squid-cache:squid:3.1.7:*:*:*:*:*:*:*

References for CVE-2011-4096

cvelogic Threat Intelligence