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Fencer Vulns
medium 5.9

CVE-2018-5131 json

Under certain circumstances the "fetch()" API can return transient local copies of resources that were sent with a "no-store" or "no-cache"…

published 2018-06-11 8 y ago modified 2026-06-17 4 mo ago also EUVD-2018-16917

cvss
5.9
version 3.0, 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

Under certain circumstances the "fetch()" API can return transient local copies of resources that were sent with a "no-store" or "no-cache" cache header instead of downloading a copy from the network as it should. This can result in previously stored, locally cached data of a website being accessible to users if they share a common profile while browsing. This vulnerability affects Firefox ESR < 52.7 and Firefox < 59.

Patch / fix

  • Mozilla Firefox ESR 52.7
  • Mozilla Firefox 59
  • firefox-esr Debian 14, Debian 13, Debian 12 52.7.0esr-1

debian advisories DEBIAN-CVE-2018-5131

  • firefox Ubuntu 14.04 LTS 59.0+build5-0ubuntu0.14.04.1
  • firefox Ubuntu 16.04 LTS 59.0+build5-0ubuntu0.16.04.1
  • firefox Ubuntu 18.04 LTS 59.0.1+build1-0ubuntu1

ubuntu advisories UBUNTU-CVE-2018-5131

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

  • firefox RHEL 7 52.7.0-1.el7_4
  • firefox RHEL 6 52.7.0-1.el6_9

red hat advisories RHSA-2018:0527RHSA-2018:0526

  • MozillaFirefox SLES for SAP 11 SP4, SLES 11 SP4, SLES 11 SP3-TERADATA +3 more 52.7.3esr-72.27.2
  • MozillaFirefox SLES for SAP 12 SP3, SLES for SAP 12 SP2, SLES for Raspberry Pi 12 SP2 +6 more 52.7.3esr-109.25.1

suse advisories SUSE-SU-2018:0907-1SUSE-SU-2018:0850-1

  • firefox-esr openSUSE Tumbleweed 128.5.1-1.1
  • MozillaFirefox openSUSE Tumbleweed 92.0-1.2

opensuse advisories openSUSE-SU-2024:14572-1openSUSE-SU-2024:10600-1

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-2018-5131 updated cvss 6.1

Mozilla: Fetch API improperly returns cached copies of no-store/no-cache resources (MFSA 2018-07)

  • Red Hat Enterprise Linux Client (v. 7) firefox 52.7.0-1.el7_4 Red Hat Enterprise Linux Client Optional (v. 7) firefox 52.7.0-1.el7_4
    fixed: vendor fix RHSA-2018:0527
  • Red Hat Enterprise Linux Desktop (v. 6) firefox 52.7.0-1.el6_9 Red Hat Enterprise Linux Desktop Optional (v. 6) firefox 52.7.0-1.el6_9
    fixed: vendor fix RHSA-2018:0526
  • Red Hat Enterprise Linux for ARM and IBM Power LE (POWER9) Server (v. 7) firefox 52.7.0-1.el7_4
    fixed: vendor fix RHSA-2018:0527
  • Red Hat Enterprise Linux HPC Node Optional (v. 6) firefox 52.7.0-1.el6_9 Red Hat Enterprise Linux Server (v. 6) firefox 52.7.0-1.el6_9
    fixed: vendor fix RHSA-2018:0526
  • Red Hat Enterprise Linux Server (v. 7) firefox 52.7.0-1.el7_4
    fixed: vendor fix RHSA-2018:0527
  • Red Hat Enterprise Linux Server Optional (v. 6) firefox 52.7.0-1.el6_9
    fixed: vendor fix RHSA-2018:0526
  • Red Hat Enterprise Linux Server Optional (v. 7) firefox 52.7.0-1.el7_4
    fixed: vendor fix RHSA-2018:0527
  • Red Hat Enterprise Linux Workstation (v. 6) firefox 52.7.0-1.el6_9
    fixed: vendor fix RHSA-2018:0526
show 4 more
  • Red Hat Enterprise Linux Workstation (v. 7) firefox 52.7.0-1.el7_4
    fixed: vendor fix RHSA-2018:0527
  • Red Hat Enterprise Linux Workstation Optional (v. 6) firefox 52.7.0-1.el6_9
    fixed: vendor fix RHSA-2018:0526
  • Red Hat Enterprise Linux Workstation Optional (v. 7) firefox 52.7.0-1.el7_4
    fixed: vendor fix RHSA-2018:0527
  • Red Hat Enterprise Linux 6 thunderbird Red Hat Enterprise Linux 7 thunderbird
    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

2.25% 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 3.0 5.9 CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:P/I:N/A:N

Affected products

  • Mozilla Firefox ESR
  • Mozilla Firefox

Classification

Weakness
  • CWE-200 Exposure of Sensitive Information to an Unauthorized Actor

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.