Security readout for executives and security teams
Plain-English summary
Firefox for Android before version 91 could remain trapped in fullscreen after actions that should restore the normal browser interface. That can reduce user visibility into browser controls and may support deceptive content, but the provided sources do not state active exploitation, CVSS severity, or broader platform impact.
Executive priority
Treat as a targeted mobile browser hygiene issue. Patch Android Firefox where present, but do not treat it as enterprise-wide critical without evidence of exploitation or broader affected platforms.
Technical view
CVE-2021-29983 is a Firefox for Android fullscreen state-handling flaw affecting Firefox versions before 91. Mozilla states other operating systems are unaffected. The bundle does not provide CWE, CVSS, exploit details, or confirmed impact beyond persistent fullscreen behavior.
Likely exposure
Exposure is limited to Android devices running Firefox below version 91. Desktop Firefox and other operating systems are stated as unaffected in the source bundle.
Exploitation context
No active exploitation is identified. The CVE is not listed as KEV in the bundle, and the provided sources do not describe public exploitation or weaponized use.
Researcher notes
Evidence is narrow: persistent fullscreen behavior, Firefox for Android only, fixed by excluding versions 91 and later. The bundle lacks CVSS, CWE, root-cause detail, and exploitability evidence, so validation should focus on version exposure and platform scoping.
Mitigation direction
- Update Firefox for Android to version 91 or later.
- Check Mozilla advisory MFSA2021-33 for vendor guidance.
- Prioritize managed Android fleets with user-facing browser access.
- Remove or restrict outdated Firefox for Android builds where patching is delayed.
Validation and detection
- Inventory Android devices for installed Firefox versions.
- Confirm Firefox for Android is version 91 or later.
- Verify desktop Firefox findings are not misclassified as this Android-only issue.
- Track exceptions where Android Firefox remains below version 91.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
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CVE-2021-29983 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS and timeline data
No CVSS vectors or timeline events were available in the normalized CVE source material.
Source materials
- CVE List V5 sourceCVE List V5
- https://www.mozilla.org/security/advisories/mfsa2021-33/CVE reference · x_refsource_MISC
- https://bugzilla.mozilla.org/show_bug.cgi?id=1719088CVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.