Skip to content
Fencer Vulns
high 7.5

CVE-2017-7843 json

When Private Browsing mode is used, it is possible for a web worker to write persistent data to IndexedDB and fingerprint a user uniquely.

published 2018-06-11 8 y ago modified 2026-06-17 4 mo ago also EUVD-2017-16818

cvss
7.5
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
2.9%
EPSS 2.9% chance of exploitation in 30 days, percentile 86%
public exploits
0
none known

Summary

When Private Browsing mode is used, it is possible for a web worker to write persistent data to IndexedDB and fingerprint a user uniquely. IndexedDB should not be available in Private Browsing mode and this stored data will persist across multiple private browsing mode sessions because it is not cleared when exiting. This vulnerability affects Firefox ESR < 52.5.2 and Firefox < 57.0.1.

Patch / fix

  • Mozilla Firefox ESR 52.5.2
  • Mozilla Firefox 57.0.1
  • firefox-esr Debian 14, Debian 13, Debian 12 52.5.2esr-1

debian advisories DEBIAN-CVE-2017-7843

  • firefox Ubuntu 14.04 LTS 57.0.1+build2-0ubuntu0.14.04.1
  • firefox Ubuntu 16.04 LTS 57.0.1+build2-0ubuntu0.16.04.1
  • firefox Ubuntu 18.04 LTS 57.0.1+build2-0ubuntu1

ubuntu advisories UBUNTU-CVE-2017-7843

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 6 52.5.1-1.el6_9
  • firefox RHEL 7 52.5.1-1.el7_4

red hat advisories RHSA-2017:3382

  • 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

  • firefox-esr Alpine 3.23, Alpine 3.22, Alpine 3.21 +14 more 52.5.2-r0

alpine advisories ALPINE-CVE-2017-7843

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

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-2017-7843 updated cvss 7.5

Mozilla: Web worker in Private Browsing mode can write IndexedDB data

  • Red Hat Enterprise Linux Client (v. 7) firefox 52.5.1-1.el7_4 Red Hat Enterprise Linux Client Optional (v. 7) firefox 52.5.1-1.el7_4 Red Hat Enterprise Linux Desktop (v. 6) firefox 52.5.1-1.el6_9 Red Hat Enterprise Linux Desktop Optional (v. 6) firefox 52.5.1-1.el6_9 Red Hat Enterprise Linux for ARM and IBM Power LE (POWER9) Server (v. 7) firefox 52.5.1-1.el7_4 Red Hat Enterprise Linux HPC Node Optional (v. 6) firefox 52.5.1-1.el6_9
    +8 more products
    Red Hat Enterprise Linux Server (v. 6) firefox 52.5.1-1.el6_9 Red Hat Enterprise Linux Server (v. 7) firefox 52.5.1-1.el7_4 Red Hat Enterprise Linux Server Optional (v. 6) firefox 52.5.1-1.el6_9 Red Hat Enterprise Linux Server Optional (v. 7) firefox 52.5.1-1.el7_4 Red Hat Enterprise Linux Workstation (v. 6) firefox 52.5.1-1.el6_9 Red Hat Enterprise Linux Workstation (v. 7) firefox 52.5.1-1.el7_4 Red Hat Enterprise Linux Workstation Optional (v. 6) firefox 52.5.1-1.el6_9 Red Hat Enterprise Linux Workstation Optional (v. 7) firefox 52.5.1-1.el7_4
    fixed: vendor fix RHSA-2017:3382

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

2.89% chance of exploitation in the next 30 days, higher than 86% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • bugzilla.mozilla.org https://bugzilla.mozilla.org/show_bug.cgi?id=1410106 referenced PoC, tagged "exploit" by a source, unverified

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:H/I:N/A:N
NVD 2.0 5.0 AV:N/AC:L/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.