Security readout for executives and security teams
Plain-English summary
This is a critical Chrome browser vulnerability that could let an attacker escape Chrome’s sandbox after first compromising the renderer. A victim would need to interact with a crafted HTML page. Because CISA lists it as known exploited, outdated Chrome installations should be treated as urgent business risk.
Executive priority
Treat as urgent for desktop and endpoint teams. The combination of critical CVSS, browser attack surface, sandbox escape potential, and CISA KEV status justifies rapid verification and remediation of all outdated Chrome installations.
Technical view
CVE-2021-37973 is a use-after-free flaw in Chrome Portals before 94.0.4606.61. The CVE states a remote attacker with a compromised renderer process could potentially perform a sandbox escape via crafted HTML. It is CWE-416 with CVSS 9.6 and scope changed impact across confidentiality, integrity, and availability.
Likely exposure
Exposure is primarily endpoints running Google Chrome before 94.0.4606.61. Fedora and Debian advisories indicate downstream browser packages also received security handling. Organizations with unmanaged browsers, delayed desktop patching, or legacy images are most likely to retain exposure.
Exploitation context
Active exploitation is supported by CISA KEV listing for CVE-2021-37973. The public bundle does not provide exploit details, campaign attribution, or proof-of-concept status. The known condition is renderer compromise followed by potential sandbox escape through crafted HTML.
Researcher notes
The source bundle supports the affected component, version floor, CWE, CVSS vector, and KEV status. It does not provide exploit mechanics or affected Chromium package version ranges beyond linked Fedora and Debian advisories, so validation should remain version and advisory based.
Mitigation direction
- Update Google Chrome to 94.0.4606.61 or later.
- Apply relevant Fedora or Debian browser security updates where applicable.
- Check vendor guidance for currently supported Chrome channels and packages.
- Prioritize unmanaged endpoints and legacy gold images.
- Retire or isolate systems unable to receive browser updates.
Validation and detection
- Inventory Chrome versions across managed and unmanaged endpoints.
- Confirm no installed Chrome version is earlier than 94.0.4606.61.
- Review Linux package status against Fedora and Debian advisories.
- Verify vulnerability scanners flag CVE-2021-37973 as remediated.
- Track KEV remediation status in vulnerability management records.
Public sources used
Michael Williams reviewed this cited source version on .
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 lookupPrivilege behavior lookup
The CVE wording references privilege impact, so privilege escalation and authorization behavior review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-37973 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
- Critical
- CVSS
- 9.6 (3.1)
- Known Exploited
- Yes
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/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:C/C:H/I:H/A:H2.86Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
9.6CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://crbug.com/1251727CVE reference · x_refsource_MISC
- https://chromereleases.googleblog.com/2021/09/stable-channel-update-for-desktop_24.htmlCVE reference · x_refsource_MISC
- FEDORA-2021-ab09a05562CVE reference · vendor-advisory, x_refsource_FEDORA
- FEDORA-2021-591b3a2af0CVE reference · vendor-advisory, x_refsource_FEDORA
- DSA-5046CVE reference · vendor-advisory, x_refsource_DEBIAN
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-37973CVE 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.