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Fencer Intel
medium 6.1

CVE-2019-18860 json

Squid before 4.9, when certain web browsers are used, mishandles HTML in the host (aka hostname) parameter to cachemgr.cgi.

published 6y ago modified 4mo ago also EUVD-2019-8556

cvss
6.1
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
5.0%
EPSS 5.0% chance of exploitation in 30 days, percentile 92%
public exploits
0
none known

Summary

Squid before 4.9, when certain web browsers are used, mishandles HTML in the host (aka hostname) parameter to cachemgr.cgi.

Patch / fix

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

debian advisories DEBIAN-CVE-2019-18860

  • squid3 Ubuntu 16.04 LTS 3.5.12-1ubuntu7.11
  • squid3 Ubuntu 18.04 LTS 3.5.27-1ubuntu1.6

ubuntu advisories UBUNTU-CVE-2019-18860

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

  • 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 3.5.21-26.26.1
  • squid SLES for SAP 15, SLES 15-LTSS, SLE Module for Server Applications 15 SP1 +2 more 4.11-5.17.2
  • squid SLES for SAP 12 SP5, SLES 12 SP5 4.11-4.9.1

suse advisories SUSE-SU-2020:14460-1SUSE-SU-2020:1803-1SUSE-SU-2020:1156-1SUSE-SU-2020:1134-1

  • squid openSUSE Tumbleweed 4.16-1.5
  • squid openSUSE Leap 15.1 4.11-lp151.2.15.2

opensuse advisories openSUSE-SU-2024:11403-1openSUSE-SU-2020:0623-1

  • 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-2019-18860 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.

Check with Fencer

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-2019-18860 updated cvss 6.1

squid: Mishandled HTML in the host parameter to cachemgr.cgi results in insecure behaviour

  • Red Hat Enterprise Linux 6 squid, squid34 Red Hat Enterprise Linux 7 squid, squid-sysvinit, squid-migration-script
    affected: workaround, no fix planned “The cachemgr.cgi script is not used by default. If you've set this up manually and are worried about this issue, remove it from your server.”
  • Red Hat Enterprise Linux 9 squid Red Hat Enterprise Linux 10 squid
    under investigation
  • 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 “The cachemgr.cgi script is not used by default. If you've set this up manually and are worried about this issue, remove it from your server.” 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

4.98% chance of exploitation in the next 30 days, higher than 92% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:N/I:P/A:N

Classification

Weakness
  • CWE-74 Improper Neutralization of Special Elements in Output Used by a Downstream Component

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.