Information disclosure in the WebExtensions component in Firefox for Android

published 2026-09-01 2 mo ago modified 2026-09-03 2 mo ago also EUVD-2026-69076

cvss: 4.3; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.3%; EPSS 0.3% chance of exploitation in 30 days, percentile 17%
public exploits: 0; none known

Information disclosure in the WebExtensions component in Firefox for Android. This vulnerability was fixed in Firefox 155.

Patch / fix

fixed in 1 distros 1

mozilla firefox_mobile 155.0

MozillaFirefox openSUSE Tumbleweed 155.0-1.1

opensuse advisories openSUSE-SU-2026:11677-1

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-2026-84127 updated 2026-11-07 cvss 6.5

firefox: Firefox: Information disclosure in WebExtensions component

Red Hat Enterprise Linux 7 firefox, firefox 140.14.0-1.el10_2 Red Hat Enterprise Linux 8 firefox, firefox 140.14.0-1.el10_2 Red Hat Enterprise Linux 9 firefox, firefox-x11, firefox 140.14.0-1.el10_2 Red Hat Enterprise Linux 10 firefox 140.14.0-1.el10_2
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

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 2 mo ago (2026-09-01)

Exploit prediction

0.26% chance of exploitation in the next 30 days, higher than 17% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

bugzilla.mozilla.org https://bugzilla.mozilla.org/show_bug.cgi?id=1699444 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CISA ADP	3.1	4.3	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N
CNA	3.1	4.3	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N

Affected products

Mozilla Firefox

Classification

Weakness

CWE-200 Exposure of Sensitive Information to an Unauthorized Actor

References

bugzilla.mozilla.org /show_bug.cgi?id=1699444
issue-tracking, exploit
mozilla.org /security/advisories/mfsa2026-82/
vendor-advisory

Sources

CVE List CVE-2026-84127
NVD CVE-2026-84127

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.

Summary