Security readout for executives and security teams
Plain-English summary
CVE-2021-30633 is a critical Chrome browser flaw in IndexedDB. A malicious web page could help an attacker escape Chrome’s sandbox after renderer compromise, raising the impact from browser compromise to broader system risk. CISA lists it as known exploited, so old Chrome versions should be treated as urgent exposure.
Executive priority
Treat this as urgent legacy exposure. It is critical severity, remotely reachable through browsing, and listed by CISA as known exploited. The main business action is rapid verification that no managed endpoints still run vulnerable Chrome versions.
Technical view
The flaw is a CWE-416 use-after-free in Chrome’s Indexed DB API before 93.0.4577.82. The CVSS 9.6 vector is network-based, low complexity, no privileges, user interaction required, scope changed, and high confidentiality, integrity, and availability impact. Exploitation requires a compromised renderer process and crafted HTML page.
Likely exposure
Exposure is primarily Chrome installations older than 93.0.4577.82. Managed desktops, kiosks, and systems with delayed browser or OS package updates are the most likely places to find residual risk. Fedora advisories indicate downstream package update relevance, but the bundle does not enumerate all affected distributions.
Exploitation context
CISA KEV inclusion supports known exploitation in the wild. The CVE text describes a remote attacker using crafted HTML after renderer compromise to potentially escape the sandbox. The sources do not provide exploit details, campaign attribution, or current exploitation volume.
Researcher notes
Key constraints matter: user interaction is required, and the sandbox escape condition assumes renderer compromise. Public sources confirm the bug class, affected Chrome threshold, and KEV status, but do not disclose reliable exploit mechanics or complete downstream affected-product scope.
Mitigation direction
- Update Chrome to 93.0.4577.82 or later, or a current vendor-supported release.
- Apply relevant OS distribution browser package updates, including Fedora advisories where applicable.
- Verify enterprise browser auto-update and patch compliance policies are enforced.
- Prioritize remediation on internet-browsing endpoints and shared kiosk systems.
- Check vendor guidance for any environment-specific hardening recommendations.
Validation and detection
- Inventory Chrome versions and flag installations below 93.0.4577.82.
- Review endpoint management reports for failed or deferred browser updates.
- Confirm Fedora or distribution package advisories are applied where relevant.
- Check CISA KEV tracking for remediation deadlines and audit expectations.
- Monitor security tooling for browser exploit or sandbox escape detections.
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
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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-2021-30633 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://chromereleases.googleblog.com/2021/09/stable-channel-update-for-desktop.htmlCVE reference · x_refsource_MISC
- https://crbug.com/1247766CVE reference · x_refsource_MISC
- FEDORA-2021-ab09a05562CVE reference · vendor-advisory, x_refsource_FEDORA
- FEDORA-2021-591b3a2af0CVE reference · vendor-advisory, x_refsource_FEDORA
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-30633CVE 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.