CVE-2016-3947

Heap-based buffer overflow in the Icmp6::Recv function in icmp/Icmp6.cc in the pinger utility in Squid before 3.5.16 and 4.x before 4.0.8 allows remote servers to cause a denial of service (performance degradation or transition failures) or write sensitive information to log files via an ICMPv6 packet.

Published: 2016-04-07 Last update: 2026-05-06 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2016-3947 is rated Moderate Risk (64/100): CVSS High severity, with high exploitation likelihood (EPSS 75.37%, 99th 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-2016-3947

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 2026-02-18 78.81% 75.37% -3.44%
2 2025-12-28 53.87% 78.81% +24.94%
3 2025-12-27 — 53.87% —

Full EPSS history (17 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2016-3947

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
8.2 3.0 HIGH
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 4.2 [email protected]
7.5 2.0 HIGH
AV:N/AC:L/Au:N/C:P/I:P/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:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 6.4 [email protected]

Weakness enumeration for CVE-2016-3947

OS Trackers for CVE-2016-3947

vendor priority summary link
debian not yet assigned CVE-2016-3947 not yet assigned priority: Debian including 1 source packages (squid), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2016-3947
gentoo normal CVE-2016-3947: 1 GLSA(s) (201607-01), 1 atom(s) (net-proxy/squid); latest impact normal. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2016-3947
redhat high — https://access.redhat.com/security/cve/CVE-2016-3947
suse medium — https://www.suse.com/security/cve/CVE-2016-3947/
ubuntu medium CVE-2016-3947 medium priority: Ubuntu including 1 source packages (squid3), 5 status rows across 5 suites (precise, trusty, upstream, wily, xenial): released 5. https://ubuntu.com/security/CVE-2016-3947

Affected software / configurations for CVE-2016-3947

Vendor Product Version Raw CPE
squid-cache squid <= 3.5.15 cpe:2.3:a:squid-cache:squid:*:*:*:*:*:*:*:*
squid-cache squid 4.0.1 cpe:2.3:a:squid-cache:squid:4.0.1:*:*:*:*:*:*:*
squid-cache squid 4.0.2 cpe:2.3:a:squid-cache:squid:4.0.2:*:*:*:*:*:*:*
squid-cache squid 4.0.3 cpe:2.3:a:squid-cache:squid:4.0.3:*:*:*:*:*:*:*
squid-cache squid 4.0.4 cpe:2.3:a:squid-cache:squid:4.0.4:*:*:*:*:*:*:*
squid-cache squid 4.0.5 cpe:2.3:a:squid-cache:squid:4.0.5:*:*:*:*:*:*:*
squid-cache squid 4.0.6 cpe:2.3:a:squid-cache:squid:4.0.6:*:*:*:*:*:*:*
squid-cache squid 4.0.7 cpe:2.3:a:squid-cache:squid:4.0.7:*:*:*:*:*:*:*
canonical ubuntu_linux 12.04 cpe:2.3:o:canonical:ubuntu_linux:12.04:*:*:*:lts:*:*:*
canonical ubuntu_linux 14.04 cpe:2.3:o:canonical:ubuntu_linux:14.04:*:*:*:lts:*:*:*
canonical ubuntu_linux 15.10 cpe:2.3:o:canonical:ubuntu_linux:15.10:*:*:*:*:*:*:*
canonical ubuntu_linux 16.04 cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:lts:*:*:*

References for CVE-2016-3947

URL Tags
http://lists.opensuse.org/opensuse-security-announce/2016-08/msg00010.html
http://lists.opensuse.org/opensuse-security-announce/2016-08/msg00040.html
http://lists.opensuse.org/opensuse-updates/2016-08/msg00069.html
http://www.securitytracker.com/id/1035457
http://www.squid-cache.org/Advisories/SQUID-2016_3.txt Vendor Advisory
http://www.squid-cache.org/Versions/v3/3.1/changesets/squid-3.1-10495.patch Patch
http://www.squid-cache.org/Versions/v3/3.2/changesets/squid-3.2-11839.patch Patch Third Party Advisory US Government Resource
http://www.squid-cache.org/Versions/v3/3.3/changesets/squid-3.3-12694.patch Patch
http://www.squid-cache.org/Versions/v3/3.4/changesets/squid-3.4-13232.patch Patch
http://www.squid-cache.org/Versions/v3/3.5/changesets/squid-3.5-14015.patch Patch
http://www.ubuntu.com/usn/USN-2995-1
https://security.gentoo.org/glsa/201607-01
cvelogic Threat Intelligence