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CVE-2021-30509: Out of bounds write in Tab Strip in Google Chrome prior to 90.0.4430.212 allowed an attacker who convinced...

Out of bounds write in Tab Strip in Google Chrome prior to 90.0.4430.212 allowed an attacker who convinced a user to install a malicious extension to perform an out of bounds memory write via a crafted HTML page and a crafted Chrome extension.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

This Chrome flaw is a browser memory-safety issue fixed in version 90.0.4430.212. The public description says exploitation required persuading a user to install a malicious extension and interact with crafted web content. That dependency lowers broad drive-by urgency but still matters where extension controls are weak.

Executive priority

Treat this as a patch-compliance and extension-governance issue. It does not justify emergency escalation from the provided evidence, but outdated browsers and unrestricted extensions create avoidable risk. Confirm fleet update status and extension controls.

Technical view

CVE-2021-30509 is an out-of-bounds write in Chrome's Tab Strip component before 90.0.4430.212. The described attack path combines a crafted HTML page with a crafted Chrome extension. Public sources do not provide CVSS, CWE, detailed impact, or confirmed exploit behavior.

Likely exposure

Exposure is most likely on unmanaged or legacy endpoints running Chrome or Chromium packages older than 90.0.4430.212, especially where users can install unapproved extensions. Gentoo and Fedora advisories indicate downstream package relevance, but the bundle does not list exact package versions.

Exploitation context

The source bundle does not show CISA KEV status or any cited active exploitation. The known precondition is user installation of a malicious extension plus crafted web content. The Chromium bug reference may not expose full technical details publicly.

Researcher notes

The useful facts are narrow: vulnerable Chrome before 90.0.4430.212, out-of-bounds write in Tab Strip, crafted HTML plus crafted extension, and downstream Linux advisories. No CVSS, CWE, exploit confirmation, or deep root-cause detail is present in the bundle.

Mitigation direction

  • Update Google Chrome to 90.0.4430.212 or a later supported version.
  • Apply relevant Chromium package updates from Gentoo, Fedora, or other OS vendors.
  • Restrict installation of unapproved browser extensions through enterprise policy.
  • Review vendor guidance for any additional platform-specific remediation.
  • Prioritize unmanaged browsers and systems outside normal patch enforcement.

Validation and detection

  • Inventory Chrome and Chromium versions across endpoints.
  • Confirm no deployed browser remains below 90.0.4430.212.
  • Check Linux package status against Gentoo and Fedora advisories.
  • Review extension allowlists for untrusted or unknown extensions.
  • Verify browser update policy enforcement on managed endpoints.
Prepared
Confidence
medium
Sources
7

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

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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CVE-2021-30509 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

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.

0CVSS vectors
0Timeline events
0ADP providers
6Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
GoogleChromeunspecifiedListed
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.