Security readout for executives and security teams
Plain-English summary
CVE-2021-21193 is a Chrome browser flaw in Blink. A vulnerable browser could be compromised after a user opens a malicious HTML page. The issue is old, but CISA lists it as known exploited, so unmanaged or legacy Chrome and Chromium installations still matter.
Executive priority
Treat as urgent cleanup if any vulnerable browsers remain. This is a known-exploited browser memory corruption issue with potential full user-context impact, but modern fully updated Chrome fleets should not be exposed.
Technical view
The vulnerability is a use-after-free in Blink affecting Google Chrome before 89.0.4389.90. 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 most likely on endpoints running Chrome or Chromium-derived distro packages that predate the March 2021 fixed releases, especially unmanaged desktops, kiosks, VDI images, or legacy Linux systems.
Exploitation context
CISA KEV inclusion supports known exploitation. The provided sources describe exploitation as possible through a crafted HTML page and do not provide exploit mechanics, campaign details, or affected non-Chrome products.
Researcher notes
Evidence supports Chrome before 89.0.4389.90, CWE-416, Blink use-after-free, crafted HTML trigger, and KEV status. The source bundle does not establish public exploit availability, detailed root cause, indicators, or downstream browser impact beyond listed Chromium package advisories.
Mitigation direction
- Update Google Chrome to 89.0.4389.90 or later.
- Update Chromium packages through Debian, Fedora, or Gentoo vendor channels where applicable.
- Prioritize any remaining vulnerable browser instances because this CVE is in CISA KEV.
- Review vendor guidance for platform-specific package names and fixed versions.
- Remove unsupported browser builds from managed endpoint images.
Validation and detection
- Inventory Chrome and Chromium versions across managed endpoints.
- Flag Chrome versions earlier than 89.0.4389.90 for remediation.
- Check Linux package status against Debian DSA-4886, Fedora, and Gentoo advisories.
- Confirm browser update policies are not pinned to obsolete releases.
- Verify vulnerable kiosk, VDI, and golden-image builds were rebuilt or retired.
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-2021-21193 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_12.htmlCVE reference · x_refsource_MISC
- https://crbug.com/1186287CVE reference · x_refsource_MISC
- DSA-4886CVE reference · vendor-advisory, x_refsource_DEBIAN
- FEDORA-2021-141d8640ceCVE reference · vendor-advisory, x_refsource_FEDORA
- GLSA-202104-08CVE reference · vendor-advisory, x_refsource_GENTOO
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-21193CVE 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.