Security readout for executives and security teams
Plain-English summary
Firefox and Firefox for Android had a WebRender race condition that Mozilla believed could potentially be exploited to run arbitrary code. The issue is fixed by moving beyond the affected versions. No source in the bundle shows active exploitation or a CVSS score.
Executive priority
Treat as a high-priority browser update issue where old Firefox versions remain in use. Urgency is strongest for managed endpoints, shared workstations, and mobile fleets that browse untrusted sites.
Technical view
CVE-2021-29952 involves undefined behavior during destruction of WebRender components. Mozilla states that, with enough effort, it may have been exploitable for arbitrary code execution. Affected versions are Firefox before 88.0.1 and Firefox for Android before 88.1.3.
Likely exposure
Exposure is mainly user workstations and Android devices running outdated Firefox versions. Server-side exposure is not indicated by the provided sources.
Exploitation context
The bundle does not cite public exploitation, KEV listing, exploit code, or in-the-wild attacks. Risk comes from browser-side memory/race-condition behavior with possible arbitrary code execution.
Researcher notes
The public data is sparse: no CVSS, CWE, or detailed bug analysis is provided in the bundle. Mozilla’s wording supports potential arbitrary code execution, but not confirmed exploitation or a reproducible attack path.
Mitigation direction
- Upgrade Firefox to 88.0.1 or later.
- Upgrade Firefox for Android to 88.1.3 or later.
- Prefer currently supported Firefox releases where possible.
- Check Mozilla advisory guidance for any environment-specific direction.
Validation and detection
- Inventory desktop Firefox versions across managed endpoints.
- Inventory Firefox for Android versions on managed mobile devices.
- Confirm no installations remain below Firefox 88.0.1.
- Confirm no Android installations remain below Firefox 88.1.3.
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
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
Execution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-29952 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/mfsa2021-20/CVE reference · x_refsource_MISC
- https://bugzilla.mozilla.org/show_bug.cgi?id=1704227CVE 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.