How severe is CVE-2016-3947?

CVE-2016-3947 has a CVSS 3.x base score of 8.2, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability high.

Is CVE-2016-3947 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 15% (96th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2016-3947?

CVE-2016-3947 primarily affects Squid-cache Squid. In total, 12 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2016-3947?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2016-3947 published?

CVE-2016-3947 was published on 2016-04-07 and last updated on 2026-06-17.

CVE-2016-3947

CVE-2016-3947 is a high-severity vulnerability in Squid-cache Squid with a CVSS 3.x base score of 8.2. Its EPSS exploit-prediction score of 15% places it in the 96th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-119.

Key facts

Severity: High (CVSS 3.x base score 8.2)
CVSS v2: 7.5
EPSS exploit prediction: 15% (96th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-119
Affected product: Squid-cache Squid
Published: 2016-04-07
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is 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.
How severe is CVE-2016-3947?: CVE-2016-3947 has a CVSS 3.x base score of 8.2, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability high.
Is CVE-2016-3947 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 15% (96th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2016-3947?: CVE-2016-3947 primarily affects Squid-cache Squid. In total, 12 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2016-3947?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2016-3947 published?: CVE-2016-3947 was published on 2016-04-07 and last updated on 2026-06-17.

References

Affected products (12)

cpe:2.3:a:squid-cache:squid:*:*:*:*:*:*:*:*
cpe:2.3:a:squid-cache:squid:4.0.1:*:*:*:*:*:*:*
cpe:2.3:a:squid-cache:squid:4.0.2:*:*:*:*:*:*:*
cpe:2.3:a:squid-cache:squid:4.0.3:*:*:*:*:*:*:*
cpe:2.3:a:squid-cache:squid:4.0.4:*:*:*:*:*:*:*
cpe:2.3:a:squid-cache:squid:4.0.5:*:*:*:*:*:*:*
cpe:2.3:a:squid-cache:squid:4.0.6:*:*:*:*:*:*:*
cpe:2.3:a:squid-cache:squid:4.0.7:*:*:*:*:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:12.04:*:*:*:lts:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:14.04:*:*:*:lts:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:15.10:*:*:*:*:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:lts:*:*:*

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Threat intelligence

Threat-intel indicators referencing this CVE:

200.89.159.59 (ipv4-addr)