CVE-2021-38003

CVE-2021-38003 is a memory corruption flaw in the V8 JavaScript engine used by Chromium, in which the engine's internal 'TheHole' sentinel value can leak into script-visible data during JSON.stringify processing (a heap-corruption condition tracked as CWE-122 and CWE-755). It is triggered when crafted JavaScript causes JSON.stringify to expose this internal value to script code. An attacker who can induce a victim to load malicious web content can leverage the resulting corruption, typically chained with further techniques, to execute code within the browser renderer or crash it. All users of Chromium-based browsers — explicitly including Google Chrome, Microsoft Edge, and Opera, and by extension other Chromium derivatives — are affected. Exploitation is confirmed in the wild: the flaw was added to CISA KEV on 2021-11-03, carries a 38.6% EPSS probability of exploitation within 30 days (98th percentile), and no public proof-of-concept is known.

What to do: Update all Chromium-based browsers (Chrome, Edge, Opera, and any Chromium-embedded or Electron-style applications in your estate) to the latest vendor-patched releases, per the CISA KEV required action to apply updates per vendor instructions. Verify remediated browser versions via enterprise update management and browser version reporting, prioritizing user workstations and externally reachable systems. Because exploitation is confirmed in the wild, treat unpatched Chromium browsers as an active exposure rather than a theoretical risk.