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Fencer Intel
high 7.5

CVE-2016-3948 in the critical feed json

Squid 3.x before 3.5.16 and 4.x before 4.0.8 improperly perform bounds checking, which allows remote attackers to cause a denial of service…

published 2016-04-07 10 y ago modified 2026-06-17 4 mo ago also EUVD-2016-4960

cvss
7.5
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
35.3%
EPSS 35.3% chance of exploitation in 30 days, percentile 98%
public exploits
0
none known

Summary

Squid 3.x before 3.5.16 and 4.x before 4.0.8 improperly perform bounds checking, which allows remote attackers to cause a denial of service via a crafted HTTP response, related to Vary headers.

Patch / fix

  • squid Debian 14, Debian 13, Debian 12 4.1-1

debian advisories DEBIAN-CVE-2016-3948

  • squid3 Ubuntu 16.04 LTS 3.5.12-1ubuntu7.5

ubuntu advisories UBUNTU-CVE-2016-3948

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • squid RHEL 7 7:3.5.20-2.el7
  • squid-sysvinit RHEL 7 7:3.5.20-2.el7
  • squid-migration-script RHEL 7 7:3.5.20-2.el7

red hat advisories RHSA-2016:2600

  • squid3 SLES for SAP 11 SP4, SLES 11 SP4 3.1.23-8.16.30.1
  • squid SLES for SAP 12 SP1, SLES 12 SP1 3.3.14-20.2

suse advisories SUSE-SU-2016:2089-1SUSE-SU-2016:2008-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2016-3948 updated cvss 5.0

squid: denial of service issue in HTTP response processing

  • Red Hat Enterprise Linux 6 squid, squid34
    affected: no fix planned “Will not fix”
  • Red Hat Enterprise Linux Server (v. 7) squid 3.5.20-2.el7, squid-migration-script 3.5.20-2.el7 Red Hat Enterprise Linux Server Optional (v. 7) squid-sysvinit 3.5.20-2.el7 Red Hat Enterprise Linux Workstation (v. 7) squid 3.5.20-2.el7, squid-migration-script 3.5.20-2.el7 Red Hat Enterprise Linux Workstation Optional (v. 7) squid-sysvinit 3.5.20-2.el7
    fixed: vendor fix RHSA-2016:2600
  • Red Hat Enterprise Linux 5 squid
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

35.27% chance of exploitation in the next 30 days, higher than 98% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 3.0 7.5 CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P

Classification

Weakness
  • CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.