CVE-2021-29961
When styling and rendering an oversized `<select>` element, Firefox did not apply correct clipping which allowed an attacker to paint over the user interface. This vulnerability affects Firefox < 89.
02 Description
When styling and rendering an oversized `<select>` element, Firefox did not apply correct clipping which allowed an attacker to paint over the user interface. This vulnerability affects Firefox < 89.
03 Exploitation and scoring
- Exploitation
- Not assessed. CISA has not published an exploitation assessment for this record, and it is not in the KEV catalog. That is an absence of assessment, not a finding of no risk.
- SSVC decision
- Not assessed by CISA
- EPSS probability
- 0.76% probability of exploitation activity in the next 30 days.
- EPSS percentile
- Equal to or higher than the score of 54.7% of scored records. A rank, not a probability.
- NVD base score
- 4.3 (CVSS v3.x), scored by the NVD independently of the CNA.
- NVD CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
- NVD analysis status
- Modified. NVD last modified this record on 2026-06-17.
- Red Hat severity
- No Red Hat rating. Red Hat rates the CVEs that affect its products.
Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.
04 Metadata
- Published
- 2021-06-24 13:15Z5 YR AGO
- Last updated
- 2024-08-03 22:18Z2 YR AGO
- Reserved
- 2021-04-01
- Assigning CNA
- mozilla
- Record state
- PUBLISHED
- Severity
- Not rated by the issuing CNA
- CNA CVSS vector
- Not published by the issuing CNA
- Weaknesses
- CWE-863Incorrect AuthorizationClass
- Data version
- 5.1
- Document digest
- a6800b4850c7e0d81dbea35dfae380f635e1b54f237b5e43874f18f4187fcc97
05 Affected products
06 References
- www.mozilla.orghttps://www.mozilla.org/security/advisories/mfsa2021-23/
- bugzilla.mozilla.orghttps://bugzilla.mozilla.org/show_bug.cgi?id=1700235
- security.gentoo.orgGLSA-202107-09https://security.gentoo.org/glsa/202107-09
07 Fixed in
Arch Linux
- firefox Fixed in 89.0-1
Source: Arch Linux Security Tracker, the Arch Linux security team. Reformatted by exploit.cc.
Ubuntu 18.04 LTS
- firefox Fixed in 89.0+build2-0ubuntu0.18.04.2
- mozjs38 No fix yet
- mozjs52 No fix yet
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu 20.04 LTS
- firefox Fixed in 89.0+build2-0ubuntu0.20.04.2
- mozjs52 No fix yet
- mozjs68 No fix yet
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu 22.04 LTS
- mozjs78 No fix yet
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
A release or ecosystem missing from this list has no record here. It may be unaffected or not covered by the source. Source notices and licences.