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Fencer Intel
high 7.5

CVE-2019-18676 json

An issue was discovered in Squid 3.x and 4.x through 4.8.

published 6y ago modified 4mo ago also EUVD-2019-8392

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
9.2%
EPSS 9.2% chance of exploitation in 30 days, percentile 95%
public exploits
0
none known

Summary

An issue was discovered in Squid 3.x and 4.x through 4.8. Due to incorrect input validation, there is a heap-based buffer overflow that can result in Denial of Service to all clients using the proxy. Severity is high due to this vulnerability occurring before normal security checks; any remote client that can reach the proxy port can trivially perform the attack via a crafted URI scheme.

Patch / fix

  • squid Debian 14, Debian 13, Debian 12 4.9-1

debian advisories DEBIAN-CVE-2019-18676

  • squid Ubuntu 20.04 LTS 4.9-2ubuntu1
  • squid3 Ubuntu 16.04 LTS 3.5.12-1ubuntu7.12
  • squid3 Ubuntu 18.04 LTS 3.5.27-1ubuntu1.7

ubuntu advisories UBUNTU-CVE-2019-18676

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 8 7:4.11-3.module+el8.3.0+7851+7808b5f9
  • libecap RHEL 8 1.0.1-2.module+el8.1.0+4044+36416a77

red hat advisories RHSA-2020:4743

  • squid SLES 11 SP4-LTSS, SLE Point of Sale 11 SP3 2.7.STABLE5-2.12.30.6.1
  • squid3 SLES 11 SP4-LTSS, SLE Point of Sale 11 SP3 3.1.23-8.16.37.12.1
  • squid SLES for SAP 12 SP4, SLES for SAP 12 SP3, SLES for SAP 12 SP2 +10 more 3.5.21-26.20.1
  • squid SLES for SAP 12 SP5, SLES 12 SP5 4.9-4.3.2
  • squid SLE Module for Server Applications 15 SP1, SLE Module for Server Applications 15 4.9-5.11.1

suse advisories SUSE-SU-2022:14908-1SUSE-SU-2020:14460-1SUSE-SU-2020:0661-1SUSE-SU-2019:3067-1SUSE-SU-2019:2975-1

  • squid openSUSE Leap 15.1 4.9-lp151.2.7.1
  • squid openSUSE Leap 15.0 4.9-lp150.13.1

opensuse advisories openSUSE-SU-2019:2541-1openSUSE-SU-2019:2540-1

  • libecap AlmaLinux 8 1.0.1-2.module_el8.6.0+2741+01592ae8

almalinux advisories ALSA-2020:4743

  • libecap Rocky Linux 8 1.0.1-2.module+el8.4.0+404+316a0dc5

rocky linux advisories RLSA-2020:4743

Is CVE-2019-18676 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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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-2019-18676 updated cvss 5.9

squid: Buffer overflow in URI processor

  • Red Hat Enterprise Linux 6 squid, squid34
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 7 squid, squid-sysvinit, squid-migration-script
    affected: no fix planned “Will not fix”
  • Red Hat Enterprise Linux AppStream (v. 8) squid 4.11-3.module+el8.3.0+7851+7808b5f9, libecap 1.0.1-2.module+el8.1.0+4044+36416a77
    fixed: vendor fix RHSA-2020:4743
  • 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

9.18% chance of exploitation in the next 30 days, higher than 95% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 3.1 7.5 CVSS:3.1/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

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.