Out-of-bounds write
A program writes outside the memory region it is allowed to use.
CWE-787 · CISA KEV; NVD record: chrome-cve-admin@google.com
Video course · Free course. C programming and memory concepts are useful; covers several weakness types.
Exploited. On CISA's list since 2026-09-09.
Google Chromium V8 Out of Bounds Write Vulnerability
CVE-2026-87491 · Google Chromium V8 · Published 2026-09-09
How bad would it be?
8.8 out of 10
CVSS rates it high.
How likely is it to be used?
3.5%
Estimated chance of exploitation in the next 30 days, higher than 89% of all scored flaws (EPSS, 2026-10-29).
Is it already being used?
Yes
CISA has seen it exploited in real attacks. For US government agencies the fix is deadline passed 37 days ago (2026-09-23).
What CISA says to do
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.
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.
What the flaw is
Out of bounds write in V8 in Google Chrome prior to 153.0.8010.36 allowed a remote attacker to execute arbitrary code inside the sandbox via a crafted HTML page. (Chromium security severity: Medium)
From the NVD.
Fixes and advisories
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CWE is a catalogue of weakness types. Labels come from the sources shown and can differ or change. Resource matches reviewed 16 October 2026.
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Exploited flaws from CISA's KEV catalogue. Chance of exploitation from EPSS by FIRST. Descriptions and scores from the NVD. This product uses the NVD API but is not endorsed or certified by the NVD.