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Exploited vulnerability · CISA KEV

Is CVE-2026-87491 exploited? Yes: in CISA KEV since 9 Sep 2026

Gociux · Google Chromium V8 · data: CISA KEV, CVE record, FIRST EPSS

Yes. CVE-2026-87491, Google Chromium V8 Out of Bounds Write Vulnerability, is being exploited in the wild. CISA added it to its Known Exploited Vulnerabilities catalog on 9 Sep 2026, the day it was published. It affects Google Chromium V8. If you run it, CISA's required action is: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

exploitedYesCISA KEV · 9 Sep 2026
ransomwareNot knownno confirmed use
EPSSbelow top 10%lower predicted activity right now (it is still confirmed exploited)
severity8.8CVSS 3.1 · high
US federal due23 Sep 2026BOD 22-01 deadline

What it is

Google Chromium V8 contains an out of bounds write vulnerability that allows a remote attacker to execute arbitrary code inside the sandbox via a crafted HTML page. This vulnerability could affect multiple web browsers that utilize Chromium, including, but not limited to, Google Chrome, Microsoft Edge, and Opera.

VendorGoogle (77 exploited CVEs in KEV)
ProductChromium V8
VulnerabilityGoogle Chromium V8 Out of Bounds Write Vulnerability
WeaknessCWE-787
Published9 Sep 2026
Added to KEV9 Sep 2026
Reported by (CNA)Chrome

What to do

  1. Check whether you run it. Look for Chromium V8 in your asset inventory, including appliances and cloud images. Stack check lists every exploited Google CVE at once.
  2. Apply the fix. Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
  3. If you can't patch today, take the affected service off the internet or restrict who can reach it, and check its logs for signs of compromise since 9 Sep 2026.
  4. Get told next time. Email alerts when CISA adds a CVE for Google.

Other exploited CVEs in Chromium V8

References

Questions

Is CVE-2026-87491 being exploited?

Yes. CISA added CVE-2026-87491 to the Known Exploited Vulnerabilities catalog on 9 Sep 2026, which means there is reliable evidence of exploitation in the wild.

Is CVE-2026-87491 used in ransomware attacks?

CISA does not list known ransomware use for it. That can change, and exploitation alone is reason to fix it first.

How do I fix CVE-2026-87491?

Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines. Check Google's advisory for the fixed versions, and if you can't patch quickly, restrict access to the affected Chromium V8 and watch it for signs of compromise.

Sources: CISA KEV (exploitation, ransomware use, required action, due date), the CVE record (publication date, CVSS, CNA), NVD and FIRST EPSS (live score). More: all KEV additions in September 2026 · Google scorecard · act-now radar.

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