Security readout for executives and security teams
Plain-English summary
CVE-2021-21166 is a Chrome audio component data race that could let a malicious web page corrupt memory after a user visits it. Google fixed it in Chrome 89.0.4389.72. Because CISA lists it in KEV, treat older Chrome builds as urgent exposure.
Executive priority
Prioritize immediate remediation for internet-browsing endpoints. This is a high-impact browser memory corruption issue with confirmed KEV status, requiring only user interaction with malicious content. Business risk is highest where browser patching is unmanaged or delayed.
Technical view
CWE-362 data race in Chrome audio before 89.0.4389.72. Attack vector is network, low complexity, no privileges, and requires user interaction. The reported impact is potential heap corruption via crafted HTML, with high confidentiality, integrity, and availability impact under CVSS 3.1 score 8.8.
Likely exposure
Endpoints running Google Chrome before 89.0.4389.72, and Linux distro Chromium packages before vendor updates. Exposure is user-driven web browsing. The bundle does not identify server-side products or non-Chromium browsers as affected.
Exploitation context
The CVE text describes exploitation through a crafted HTML page. CISA KEV inclusion indicates known exploitation, but the supplied sources do not provide public exploit mechanics, scope, or campaign attribution. Avoid assuming compromise without telemetry.
Researcher notes
The useful technical facts are limited: vulnerable Chrome audio code, data race, potential heap corruption, crafted HTML trigger, and fixed Chrome release. The linked Chromium bug may have access restrictions. No exploit details or reliable indicators are included in the supplied bundle.
Mitigation direction
- Upgrade Google Chrome to 89.0.4389.72 or later.
- Apply relevant Fedora, Debian, or Gentoo Chromium security updates where applicable.
- Prioritize managed endpoint browser patch compliance for all user workstations.
- Check vendor guidance for any platform-specific remediation not covered here.
Validation and detection
- Inventory Chrome and Chromium versions across managed endpoints.
- Flag any Chrome version older than 89.0.4389.72.
- Confirm Linux package advisories are applied on affected distributions.
- Review EDR or proxy telemetry for suspicious browser crash or exploit indicators.
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.
CWE-362: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2021-21166 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
- High
- CVSS
- 8.8 (3.1)
- Known Exploited
- Yes
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
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.
CISA KEV status
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H2.85.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
8.8HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://chromereleases.googleblog.com/2021/03/stable-channel-update-for-desktop.htmlCVE reference · x_refsource_MISC
- https://crbug.com/1177465CVE reference · x_refsource_MISC
- FEDORA-2021-c88a96bd4bCVE reference · vendor-advisory, x_refsource_FEDORA
- FEDORA-2021-4740239e28CVE reference · vendor-advisory, x_refsource_FEDORA
- FEDORA-2021-78547312f2CVE reference · vendor-advisory, x_refsource_FEDORA
- DSA-4886CVE reference · vendor-advisory, x_refsource_DEBIAN
- GLSA-202104-08CVE reference · vendor-advisory, x_refsource_GENTOO
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-21166CVE reference · government-resource
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.
Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.