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Fencer Vulns
medium 5.9

CVE-2018-18506 json

When proxy auto-detection is enabled, if a web server serves a Proxy Auto-Configuration (PAC) file or if a PAC file is loaded locally, this…

published 2019-02-05 7 y ago modified 2026-06-17 4 mo ago also EUVD-2018-10231

cvss
5.9
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
2.2%
EPSS 2.2% chance of exploitation in 30 days, percentile 82%
public exploits
0
none known

Summary

When proxy auto-detection is enabled, if a web server serves a Proxy Auto-Configuration (PAC) file or if a PAC file is loaded locally, this PAC file can specify that requests to the localhost are to be sent through the proxy to another server. This behavior is disallowed by default when a proxy is manually configured, but when enabled could allow for attacks on services and tools that bind to the localhost for networked behavior if they are accessed through browsing. This vulnerability affects Firefox < 65.

Patch / fix

  • Mozilla Firefox 65
  • firefox-esr Debian 14, Debian 13, Debian 12 60.6.0esr-1
  • thunderbird Debian 14, Debian 13, Debian 12 1:60.6.1-1

debian advisories DEBIAN-CVE-2018-18506

  • firefox Ubuntu 14.04 LTS 65.0+build2-0ubuntu0.14.04.1
  • firefox Ubuntu 16.04 LTS 65.0+build2-0ubuntu0.16.04.1
  • firefox Ubuntu 18.04 LTS 65.0+build2-0ubuntu0.18.04.1
  • thunderbird Ubuntu 14.04 LTS 1:60.6.1+build2-0ubuntu0.14.04.1
  • thunderbird Ubuntu 16.04 LTS 1:60.6.1+build2-0ubuntu0.16.04.1
  • thunderbird Ubuntu 18.04 LTS 1:60.6.1+build2-0ubuntu0.18.04.1

ubuntu advisories UBUNTU-CVE-2018-18506

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

  • thunderbird RHEL 8 60.6.1-1.el8
  • thunderbird RHEL 7 60.6.1-1.el7_6
  • firefox RHEL 8 60.6.1-1.el8
  • thunderbird RHEL 6 60.6.1-1.el6_10
  • firefox RHEL 6 60.6.0-3.el6_10
  • firefox RHEL 7 60.6.0-3.el7_6

red hat advisories RHSA-2019:1144RHSA-2019:0681RHSA-2019:0966RHSA-2019:0680RHSA-2019:0623RHSA-2019:0622

  • MozillaFirefox SLE Module for Desktop Applications 15 60.6.1-3.29.3
  • MozillaThunderbird SLE Workstation Extension 15 60.6.1-3.28.1
  • MozillaFirefox SLES for SAP 12 SP4, SLES for SAP 12 SP3, SLES for SAP 12 SP2 +13 more 60.6.1esr-109.63.2

suse advisories SUSE-SU-2019:0871-1SUSE-SU-2019:0853-1SUSE-SU-2019:0852-1

  • firefox-esr openSUSE Tumbleweed 128.5.1-1.1
  • MozillaFirefox openSUSE Tumbleweed 92.0-1.2
  • MozillaThunderbird openSUSE Leap 15.0 60.6.1-lp150.3.37.1
  • MozillaThunderbird Package Hub 12 60.6.1-82.1
  • MozillaFirefox openSUSE Leap 15.0 60.6.1-lp150.3.45.1

opensuse advisories openSUSE-SU-2024:14572-1openSUSE-SU-2024:10600-1openSUSE-SU-2019:1162-1openSUSE-SU-2019:1126-1openSUSE-SU-2019:1077-1

  • firefox-esr Alpine 3.23, Alpine 3.22, Alpine 3.21 +12 more 60.6.1-r0

alpine advisories ALPINE-CVE-2018-18506

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • firefox Arch Linux 65.0-1

arch linux advisories AVG-862

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-2018-18506 updated cvss 6.1

Mozilla: Proxy Auto-Configuration file can define localhost access to be proxied

  • Red Hat Enterprise Linux AppStream (v. 8) firefox 60.6.1-1.el8, thunderbird 60.6.1-1.el8
    fixed: vendor fix RHSA-2019:0966
  • Red Hat Enterprise Linux Client (v. 7) firefox 60.6.0-3.el7_6, thunderbird 60.6.1-1.el7_6 Red Hat Enterprise Linux Client Optional (v. 7) firefox 60.6.0-3.el7_6
    fixed: vendor fix RHSA-2019:0622
  • Red Hat Enterprise Linux Desktop (v. 6) firefox 60.6.0-3.el6_10, thunderbird 60.6.1-1.el6_10 Red Hat Enterprise Linux Desktop Optional (v. 6) firefox 60.6.0-3.el6_10
    fixed: vendor fix RHSA-2019:0623
  • Red Hat Enterprise Linux for ARM and IBM Power LE (POWER9) Server (v. 7) firefox 60.6.0-3.el7_6
    fixed: vendor fix RHSA-2019:0622
  • Red Hat Enterprise Linux for ARM and IBM Power LE (POWER9) Server Optional (v. 7) thunderbird 60.6.1-1.el7_6
    fixed: vendor fix RHSA-2019:0681
  • Red Hat Enterprise Linux HPC Node Optional (v. 6) firefox 60.6.0-3.el6_10 Red Hat Enterprise Linux Server (v. 6) firefox 60.6.0-3.el6_10
    fixed: vendor fix RHSA-2019:0623
  • Red Hat Enterprise Linux Server (v. 7) firefox 60.6.0-3.el7_6
    fixed: vendor fix RHSA-2019:0622
  • Red Hat Enterprise Linux Server Optional (v. 6) firefox 60.6.0-3.el6_10, thunderbird 60.6.1-1.el6_10
    fixed: vendor fix RHSA-2019:0623
show 5 more
  • Red Hat Enterprise Linux Server Optional (v. 7) firefox 60.6.0-3.el7_6, thunderbird 60.6.1-1.el7_6
    fixed: vendor fix RHSA-2019:0622
  • Red Hat Enterprise Linux Workstation (v. 6) firefox 60.6.0-3.el6_10, thunderbird 60.6.1-1.el6_10
    fixed: vendor fix RHSA-2019:0623
  • Red Hat Enterprise Linux Workstation (v. 7) firefox 60.6.0-3.el7_6, thunderbird 60.6.1-1.el7_6
    fixed: vendor fix RHSA-2019:0622
  • Red Hat Enterprise Linux Workstation Optional (v. 6) firefox 60.6.0-3.el6_10
    fixed: vendor fix RHSA-2019:0623
  • Red Hat Enterprise Linux Workstation Optional (v. 7) firefox 60.6.0-3.el7_6
    fixed: vendor fix RHSA-2019:0622

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

2.20% chance of exploitation in the next 30 days, higher than 82% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:N/I:P/A:N

Affected products

  • Mozilla Firefox

References

Sources

Fencer Vulns 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.