Security readout for executives and security teams
Plain-English summary
CVE-2021-21206 is a high-severity Google Chrome flaw in Blink. A malicious web page could trigger memory corruption if a user visits it. Because CISA lists it in KEV, treat outdated Chrome installations as urgent exposure, especially on user workstations and managed browser fleets.
Executive priority
Prioritize remediation because this is browser-facing, requires only user interaction, has high potential impact, and appears in CISA KEV. The business risk is highest where outdated browsers are used for daily web access.
Technical view
The vulnerability is a CWE-416 use-after-free in Blink before Chrome 89.0.4389.128. The CVSS 3.1 score is 8.8, with network attack vector, low complexity, no privileges required, user interaction required, and high confidentiality, integrity, and availability impact.
Likely exposure
Exposure is likely where Google Chrome versions earlier than 89.0.4389.128 remain installed. The bundle also references Gentoo and Fedora advisories, so Linux package-managed browser deployments should be checked against those vendor updates.
Exploitation context
CISA KEV inclusion supports known exploitation. The public description says exploitation could occur through a crafted HTML page and heap corruption, but the bundle does not provide campaign details, exploit maturity, or attacker tooling specifics.
Researcher notes
Evidence supports a Blink use-after-free leading to possible heap corruption via crafted HTML. Public details in the bundle are limited; avoid assuming exploit chains, sandbox escape behavior, or affected downstream products beyond the cited advisories.
Mitigation direction
- Upgrade Google Chrome to 89.0.4389.128 or later.
- Apply relevant Gentoo or Fedora browser package updates where applicable.
- Use enterprise browser management to enforce minimum Chrome versions.
- Prioritize internet-browsing workstations and high-risk user groups.
- Review vendor advisories before applying distribution-specific package actions.
Validation and detection
- Inventory Chrome versions across managed endpoints.
- Flag any Chrome installation older than 89.0.4389.128.
- Confirm Linux hosts received applicable Gentoo or Fedora updates.
- Check browser management reports for update failures or pinned versions.
- Document remediation status for KEV tracking and audit evidence.
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-416: 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-2021-21206 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://crbug.com/1196781CVE reference · x_refsource_MISC
- https://chromereleases.googleblog.com/2021/04/stable-channel-update-for-desktop.htmlCVE reference · x_refsource_MISC
- GLSA-202104-08CVE reference · vendor-advisory, x_refsource_GENTOO
- FEDORA-2021-c3754414e7CVE reference · vendor-advisory, x_refsource_FEDORA
- FEDORA-2021-ff893e12c5CVE reference · vendor-advisory, x_refsource_FEDORA
- FEDORA-2021-35d2bb4627CVE reference · vendor-advisory, x_refsource_FEDORA
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-21206CVE 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.
Use After Free
Use After Free represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.