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PatchSiren cyber security CVE debrief

CVE-2021-21166 Google CVE debrief

CVE-2021-21166 is identified in the supplied sources as a Google Chromium race condition vulnerability and was added to CISA’s Known Exploited Vulnerabilities catalog on 2021-11-03. Because CISA lists it as known exploited, it should be treated as a patching priority for any environment using Chromium or Chromium-based browsers.

Vendor
Google
Product
Chromium
CVSS
Unknown
CISA KEV
Listed
Original CVE published
2021-11-03
Original CVE updated
2021-11-03
Advisory published
2021-11-03
Advisory updated
2021-11-03

Who should care

Security and endpoint teams responsible for Chromium-based browser fleets, desktop patch management, and vulnerability remediation should prioritize this issue, especially where browser updates are centrally managed.

Technical summary

The supplied corpus describes CVE-2021-21166 only at a high level as a race condition in Google Chromium. CISA’s KEV entry confirms it is known exploited and directs organizations to apply updates per vendor instructions. No CVSS score or deeper technical breakdown was provided in the supplied data.

Defensive priority

High

Recommended defensive actions

  • Apply Google’s vendor-recommended updates for Chromium as soon as possible.
  • Verify whether any Chromium-based browsers or embedded Chromium components are present in your environment.
  • Track remediation against CISA’s KEV due date of 2021-11-17.
  • Confirm endpoint coverage and update compliance across managed devices.
  • Use the official CVE and NVD records to map internal asset exposure and remediation status.

Evidence notes

Evidence is limited to the supplied source corpus and official links. The corpus identifies Google as the vendor, Chromium as the product, and CISA KEV as the authority listing the issue on 2021-11-03 with a due date of 2021-11-17. The supplied data does not include a CVSS score or further technical detail beyond the race condition description.

Sources and references

Verified primary and authoritative sources

  • CVE-2021-21166 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2021-21166

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2021-21166 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2021-21166

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

  • CISA Known Exploited Vulnerabilities catalog

    Publisher, destination, and source semantics verified

    URL: https://www.cisa.gov/known-exploited-vulnerabilities-catalog

    Cybersecurity and Infrastructure Security Agency - Official CISA catalog of vulnerabilities known to be exploited in the wild.

Supplemental references

  • Source item URL

    Unverified legacy reference

    URL: https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json

    cisa_kev

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.