CVE-2021-29971

If a user had granted a permission to a webpage and saved that grant, any webpage running on the...

9.8 Critical

If a user had granted a permission to a webpage and saved that grant, any webpage running on the same host - irrespective of scheme or port - would be granted that permission. This bug only affects Firefox for Android. Other operating systems are unaffected.. This vulnerability affects Firefox < 90.

Attack profile

How easy it is to exploit

Attack vector: Network
Complexity: Low
Privileges needed: None
User interaction: None

What an attacker can affect

Confidentiality: High
Integrity: High
Availability: High

Exploit likelihood

1.02%Up 0.4 points since Aug 6, 2021

What each source reports

NVD Score used 9.8

Record: CVE-2021-29971
CVSS 3.1: 9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS 2.0: 7.5 HighAV:N/AC:L/Au:N/C:P/I:P/A:P
Weakness: CWE-281
Updated: 2026-11-02

CVE List No score

Record: CVE-2021-29971
Updated: 2026-11-02

EUVDEUVD-2021-16430 No score

Record: EUVD-2021-16430
Updated: 2026-11-03

GitHub AdvisoriesGHSA-hmhq-whfw-x78q No score

If a user had granted a permission to a webpage and saved that grant, any webpage running on the...

Record: GHSA-hmhq-whfw-x78q
Weakness: CWE-281
Updated: 2026-11-02

OSVUBUNTU-CVE-2021-29971 9.8

Record: UBUNTU-CVE-2021-29971
CVSS 3.1: 9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated: 2026-11-02

OSVopenSUSE-SU-2024:10600-1 No score

MozillaFirefox-92.0-1.2 on GA media

These are all security issues fixed in the MozillaFirefox-92.0-1.2 package on the GA media of openSUSE Tumbleweed.

Record: openSUSE-SU-2024:10600-1
Updated: 2026-11-02

OSVopenSUSE-SU-2024:14572-1 No score

firefox-esr-128.5.1-1.1 on GA media

These are all security issues fixed in the firefox-esr-128.5.1-1.1 package on the GA media of openSUSE Tumbleweed.

Record: openSUSE-SU-2024:14572-1
Updated: 2026-11-02

Affected products

mozilla firefox

Affected packages

Affected packages
Package	Affected	Fixed
`mozjs52` Ubuntu:18.04:LTS	All versions, plus listed versions 52.3.1-0ubuntu352.3.1-7fakesync152.8.1-0ubuntu0.18.04.152.9.1-0ubuntu0.18.04.1	None known
`mozjs38` Ubuntu:18.04:LTS	All versions, plus listed versions 38.8.0~repack1-0ubuntu138.8.0~repack1-0ubuntu338.8.0~repack1-0ubuntu4	None known
`mozjs68` Ubuntu:20.04:LTS	All versions, plus listed versions 68.5.0-1~fakesync68.5.0-2~fakesync68.6.0-168.6.0-1ubuntu1	None known
`mozjs52` Ubuntu:20.04:LTS	All versions, plus listed versions 52.9.1-1build152.9.1-1ubuntu3	None known
`mozjs78` Ubuntu:22.04:LTS	All versions, plus listed versions 78.13.0-178.15.0-278.15.0-4ubuntu1	None known
`MozillaFirefox` openSUSE:Tumbleweed From an advisory covering 661 CVEs	before 92.0-1.2	92.0-1.2
`firefox-esr` openSUSE:Tumbleweed From an advisory covering 1860 CVEs	before 128.5.1-1.1	128.5.1-1.1

History

History
Recorded	Changed	Sources
Nov 6, 2026	affected, facts
Nov 3, 2026	aliases	EUVD
Nov 2, 2026	first indexed	CVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2021-29971 is a critical vulnerability (CVSS 9.8) in Mozilla Firefox, published August 5, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.02%, the 63rd percentile. No source names a fixed version.

References

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