CVE-2021-24000

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 &lt;input type="file"&gt;) 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.

Published: 2021-06-24 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-24000 is rated Low Risk (28.2/100): CVSS Low severity, with low exploitation likelihood (EPSS 0.60%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2021-24000

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.23% 0.60% +0.37%
2 2025-03-30 0.48% 0.23% -0.25%
3 2025-03-29 — 0.48% —

Full EPSS history (9 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-24000

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
3.1 3.1 LOW
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 1.6 1.4 [email protected]
2.6 2.0 LOW
AV:N/AC:H/Au:N/C:P/I:N/A:N Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:H)
Exploitation requires uncommon or highly specific conditions.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:N)
No availability impact.
 4.9 2.9 [email protected]

Weakness enumeration for CVE-2021-24000

OS Trackers for CVE-2021-24000

vendor priority summary link
alpine low CVE-2021-24000: 2 source package rows (firefox, librewolf); 48 state rows across 7 repos (3.17-community, 3.18-community, 3.19-community, 3.20-community, 3.21-community, 3.22-community, edge-community); fixed 10, open 38. https://security.alpinelinux.org/vuln/CVE-2021-24000
debian not yet assigned CVE-2021-24000 not yet assigned priority: Debian including 1 source packages (firefox), 1 status rows across 1 suites (sid): resolved 1. https://security-tracker.debian.org/tracker/CVE-2021-24000
suse high CVE-2021-24000 severity important: SUSE including 9 source package names (MozillaFirefox-92.0-1.2, MozillaFirefox-branding-upstream-92.0-1.2, …), 9 product×package rows across 1 product lines (openSUSE Tumbleweed): Fixed 9. https://www.suse.com/security/cve/CVE-2021-24000/
ubuntu medium CVE-2021-24000 medium priority: Ubuntu including 5 source packages (firefox, mozjs38, mozjs52, mozjs68, mozjs78), 65 status rows across 13 suites (bionic, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, trusty, upstream, xenial): DNE 37, ignored 16, released 12. https://ubuntu.com/security/CVE-2021-24000

Affected software / configurations for CVE-2021-24000

Vendor Product Version Raw CPE
mozilla firefox < 88.0 cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*

References for CVE-2021-24000

URL Tags
https://bugzilla.mozilla.org/show_bug.cgi?id=1694698 Issue Tracking Permissions Required Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2021-16/ Release Notes Vendor Advisory
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