{"id":"CVE-2026-87491","published":"2026-09-09T01:17:05Z","modified":"2026-09-21T13:17:11Z","title":"Google Chromium V8 Out of Bounds Write Vulnerability","vendor":"Google","product":"Chromium V8","tier":"core","eol":null,"description":{"text":"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)","provenance":"source","from":"NVD"},"summary":{"text":"The vulnerability is an out-of-bounds write in the V8 JavaScript engine component of Google Chrome, which is Google's Chromium V8 product. An attacker who can get a victim to open a crafted HTML page can execute arbitrary code inside the browser sandbox, with no authentication required but user interaction needed to load the page.","provenance":"ai","model":"claude-haiku-5-5","generatedAt":"2026-10-23T07:13:50Z"},"cvss":{"score":8.8,"severity":"HIGH","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","provenance":"source","from":"NVD"},"epss":{"score":0.03507,"percentile":0.89175,"date":"2026-10-30","provenance":"source"},"kev":{"dateAdded":"2026-09-09","dueDate":"2026-09-23","ransomware":false,"requiredAction":"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.","notes":"https://chromereleases.googleblog.com/2026/09/stable-channel-update-for-desktop_0808145027.html ; BOD 26-04: https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk ; Forensics Triage Requirements: https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk ; https://nvd.nist.gov/vuln/detail/CVE-2026-87491 ","provenance":"source"},"vulncheckKev":{"dateAdded":"2026-09-08","exploitedFirstSeen":"2026-09-08","ransomware":false,"evidence":[{"url":"https://chromereleases.googleblog.com/2026/09/stable-channel-update-for-desktop_0808145027.html","date":"2026-09-08"},{"url":"https://docs.google.com/spreadsheets/d/1lkNJ0uQwbeC1ZTRrxdtuPLCIl7mlUreoKfSIgajnSyY/edit","date":"2026-09-08"},{"url":"https://previdian.com/CVE-2026-87491","date":"2026-09-09"},{"url":"https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json","date":"2026-09-09"},{"url":"https://www.volexity.com/blog/2026/09/09/mind-the-patch-gap-multiple-chinese-threat-actors-chain-0-day-exploits-in-chrome-windows/","date":"2026-09-09"},{"url":"https://www.proofpoint.com/us/blog/threat-insight/once-bluemoon-multiple-state-aligned-threat-actors-rapidly-adopt-novel-exploit","date":"2026-09-14"},{"url":"https://www.volexity.com/blog/2026/09/21/mind-the-patch-gap-part-2-fake-websites-used-to-deploy-chrome-windows-0-day-exploits/","date":"2026-09-21"}],"evidenceTotal":7,"provenance":"source"},"exploited":true,"otx":{"pulseCount":47,"pulses":[{"name":"Actively_Exploited_Kev | Oct 31, 2026","url":"https://otx.alienvault.com/pulse/6ae4aefab0c2191cecd41862","created":"2026-10-30"},{"name":"Actively_Exploited_Kev | Oct 30, 2026","url":"https://otx.alienvault.com/pulse/6ae35d889ea92b4ce19c2680","created":"2026-10-29"},{"name":"Actively_Exploited_Kev | Oct 29, 2026","url":"https://otx.alienvault.com/pulse/6ae20c1db17e7057ae7d9ad1","created":"2026-10-28"},{"name":"Actively_Exploited_Kev | Oct 28, 2026","url":"https://otx.alienvault.com/pulse/6ae0ba7e0e2a97ff7b218819","created":"2026-10-27"},{"name":"Actively_Exploited_Kev | Oct 27, 2026","url":"https://otx.alienvault.com/pulse/6adf68b85c3e852f3c111d18","created":"2026-10-26"},{"name":"Actively_Exploited_Kev | Oct 24, 2026","url":"https://otx.alienvault.com/pulse/6adb740e397c3ad4799aa4cd","created":"2026-10-23"},{"name":"Actively_Exploited_Kev | Oct 23, 2026","url":"https://otx.alienvault.com/pulse/6ada236fcfba2dfa730ea482","created":"2026-10-22"},{"name":"Actively_Exploited_Kev | Oct 22, 2026","url":"https://otx.alienvault.com/pulse/6ad8d33a077cbb5cab524d80","created":"2026-10-21"},{"name":"Actively_Exploited_Kev | Oct 21, 2026","url":"https://otx.alienvault.com/pulse/6ad78130c4d1ac2be83a8b6d","created":"2026-10-20"},{"name":"Actively_Exploited_Kev | Oct 20, 2026","url":"https://otx.alienvault.com/pulse/6ad62f63c24a405a3423cc13","created":"2026-10-19"}],"provenance":"machine"},"cwes":[{"id":"CWE-787","name":"Out-of-bounds Write"}],"references":[{"url":"https://chromereleases.googleblog.com/2026/09/stable-channel-update-for-desktop_0808145027.html","tags":["Release Notes","Vendor Advisory"]},{"url":"https://issues.chromium.org/issues/543557673","tags":["Permissions Required"]},{"url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-87491","tags":["US Government Resource"]}],"techniques":[{"id":"T1189","name":"Drive-by Compromise","tactics":["initial-access"],"provenance":"ai","basis":"ai-mapping","bases":["ai-mapping"],"basisDetail":"claude-haiku-5-5: Malicious webpage triggers the browser exploit","mappingType":"exploitation_technique","evidence":[{"from":"description","quote":"via a crafted HTML page","start":137,"end":160}],"model":"claude-haiku-5-5","confidence":"medium","confidenceNote":"AI-mapped from the description (quote-validated, not expert-reviewed)"},{"id":"T1059","name":"Command and Scripting Interpreter","tactics":["execution"],"provenance":"ai","basis":"ai-mapping","bases":["ai-mapping"],"basisDetail":"claude-haiku-5-5: Attacker runs arbitrary code in renderer sandbox","mappingType":"primary_impact","evidence":[{"from":"description","quote":"execute arbitrary code inside the sandbox","start":95,"end":136}],"model":"claude-haiku-5-5","confidence":"medium","confidenceNote":"AI-mapped from the description (quote-validated, not expert-reviewed)"}],"reports":[],"affected":[],"advisories":[],"euvd":{"id":"EUVD-2026-74529","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-74529","exploited":true,"exploitedSince":"2026-09-09","provenance":"source"},"exploits":[],"exploitSources":{"pocGithub":{"count":1,"skipped":0,"earliest":"2026-09-10","earliestUrl":"https://github.com/SneakyNachos/CVE-2026-87491-and-CVE-2026-85046-the-bagel-fell-off-the-counter","repos":[{"name":"SneakyNachos/CVE-2026-87491-and-CVE-2026-85046-the-bagel-fell-off-the-counter","url":"https://github.com/SneakyNachos/CVE-2026-87491-and-CVE-2026-85046-the-bagel-fell-off-the-counter","stars":5,"created":"2026-09-10"}]},"first":{"date":"2026-09-10","source":"PoC-in-GitHub","url":"https://github.com/SneakyNachos/CVE-2026-87491-and-CVE-2026-85046-the-bagel-fell-off-the-counter"},"provenance":"source"},"exploitRefs":[],"flow":[{"stage":"exploitation","techniques":["T1189"],"provenance":"ai"},{"stage":"primary","techniques":["T1059"],"provenance":"ai"}],"timeline":[{"date":"2026-09-08","kind":"exploited-reported","label":"Exploitation 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