CVE-2021-29987
This vulnerability affects Firefox < 91 and Thunderbird < 91.
Does this matter?
Lower severity and a low EPSS score (0.95%). Track it; it rarely justifies an emergency change on its own.
Description
After requesting multiple permissions, and closing the first permission panel, subsequent permission panels will be displayed in a different position but still record a click in the default location, making it possible to trick a user into accepting a permission they did not want to. *This bug only affects Firefox on Linux. Other operating systems are unaffected.*. This vulnerability affects Firefox < 91 and Thunderbird < 91.
- CVSS 3.1
- 6.5 MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
- EPSS
- 0.95% probability · 61th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-307
- Affected
- mozilla/firefox · mozilla/thunderbird
- Source
- security@mozilla.org
EPSS 0.9% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=1716129Issue Tracking, Vendor Advisory
- https://security.gentoo.org/glsa/202202-03Third Party Advisory
- https://www.mozilla.org/security/advisories/mfsa2021-33/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2021-36/Vendor Advisory
- https://bugzilla.mozilla.org/show_bug.cgi?id=1716129Issue Tracking, Vendor Advisory
- https://security.gentoo.org/glsa/202202-03Third Party Advisory
- https://www.mozilla.org/security/advisories/mfsa2021-33/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2021-36/Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.