A race condition with requestPointerLock() and setTimeout() could have resulted in a user interacting with one tab when they believed they…

published 2021-06-24 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-10920

cvss: 3.1; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 0.6%; EPSS 0.6% chance of exploitation in 30 days, percentile 49%
public exploits: 0; none known

A race condition with requestPointerLock() and setTimeout() could have resulted in a user interacting with one tab when they believed they were on a separate tab. In conjunction with certain elements (such as <input type="file">) this could have led to an attack where a user was confused about the origin of the webpage and potentially disclosed information they did not intend to. This vulnerability affects Firefox < 88.

Patch / fix

fixed in 1 distros 4

Mozilla Firefox 88

ubuntu opensuse alpine arch linux

firefox Ubuntu 16.04 LTS 88.0+build2-0ubuntu0.16.04.1
firefox Ubuntu 18.04 LTS 88.0+build2-0ubuntu0.18.04.2
firefox Ubuntu 20.04 LTS 88.0+build2-0ubuntu0.20.04.1

ubuntu advisories UBUNTU-CVE-2021-24000

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

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

firefox Alpine 3.23, Alpine 3.22, Alpine 3.21 +8 more 88.0-r0
librewolf Alpine 3.24, Alpine 3.23, Alpine 3.22 +1 more 88.0-r0

alpine advisories ALPINE-CVE-2021-24000

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 88.0-1

arch linux advisories AVG-1834

Exploit prediction

0.60% chance of exploitation in the next 30 days, higher than 49% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
NVD	3.1	3.1	CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N
NVD	2.0	2.6	AV:N/AC:H/Au:N/C:P/I:N/A:N

Affected products

Mozilla Firefox

Classification

Weakness

CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization

References

mozilla.org /security/advisories/mfsa2021-16/
release-notes, vendor-advisory
bugzilla.mozilla.org /show_bug.cgi?id=1694698
issue-tracking, permissions-required, vendor-advisory

Sources

CVE List CVE-2021-24000
NVD CVE-2021-24000

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