Zero-Day Alert: Google Chrome Under Active Attack, Exploiting New Vulnerability

CVE-2023-2033 is a type confusion flaw (CWE-843) in Google's Chromium V8 JavaScript engine that a remote attacker can trigger by convincing a user to load a crafted HTML page. Successful exploitation could lead to heap corruption in the browser, potentially allowing the attacker to execute code in the context of the affected browser. Because V8 underpins the entire Chromium ecosystem, users of Google Chrome, Microsoft Edge, Opera, and any other Chromium-based browser or application are potentially affected. The flaw is already being exploited: CISA added it to the Known Exploited Vulnerabilities catalog on 2023-04-17, and EPSS assigns a 40.8% probability of exploitation within 30 days (99th percentile), though no public proof-of-concept is known and ransomware use is unknown.

Do: Update Google Chrome and every other Chromium-based browser in use (Microsoft Edge, Opera, Brave, etc.) to the latest vendor-supplied stable release, per CISA's KEV required action to apply updates per vendor instructions. Verify installed browser versions across managed endpoints and treat unpatched Chromium builds as actively exploited given the KEV listing and high EPSS score.

An integer overflow (CWE-190) in Skia, the 2D graphics library used by Chrome's renderer, can be triggered by a crafted HTML page whose content drives Skia processing past the limits of its integer math. A remote attacker who has already compromised the Chrome renderer process — for example through a separate renderer flaw or a malicious page — can leverage the overflow to escape Chrome's renderer sandbox and gain broader code execution on the host. All Google Chrome and Chromium users running versions prior to 112.0.5615.137 are affected, including Chromium packages shipped by Debian and Fedora. The flaw is rated Critical (CVSS 3.1: 9.6) and carries Chromium security severity High, with an EPSS probability of 5.7% (93rd percentile) of exploitation within 30 days. It was added to CISA's Known Exploited Vulnerability catalog on 2023-04-21, and news reports describe it as an actively exploited Chrome zero-day for which Google rushed out the 112.0.5615.137 patch.

Do: Update Google Chrome to 112.0.5615.137 or later on all platforms, and install the corresponding Chromium security updates on Debian and Fedora systems. Because exploitation requires user interaction with a crafted page plus a pre-existing renderer compromise, prompt patching is the primary mitigation; verify via CISA KEV required actions that all managed browsers are updated and confirm Chrome versions in endpoint inventory.

CVE-2023-3079 is a type confusion vulnerability (CWE-843) in the V8 JavaScript engine that powers Google Chromium, triggerable remotely when a user visits or is directed to a specially crafted HTML page. Successful exploitation causes heap corruption, which a remote attacker can leverage to execute code within the affected browser's renderer process. Every browser or application built on the Chromium engine is potentially affected, explicitly including Google Chrome, Microsoft Edge, and Opera. The flaw is being exploited in the wild: CISA added it to the Known Exploited Vulnerabilities catalog on 2023-06-07 with a required action to apply vendor updates, and EPSS assigns a 32.1% probability of exploitation activity in the next 30 days (98th percentile). No public proof-of-concept code is known, but the KEV listing confirms real-world attacks, making rapid patching of all Chromium-based browsers a priority.

Do: Immediately update Google Chrome, Microsoft Edge, Opera, and any other Chromium-based browsers (including Chromium-embedded applications) to the latest vendor release, per the CISA KEV required action to apply updates per vendor instructions; confirm the update applied via the browser's About/Settings page. As a stopgap where patching is delayed, restrict browsing to trusted sites or disable JavaScript where feasible, since exploitation requires the renderer to process a crafted HTML page.

CVE-2023-4762 is a type confusion bug (CWE-843) in the V8 JavaScript engine used by Google Chromium, allowing a remote attacker to execute arbitrary code in the context of the browser when a user visits or is redirected to a crafted HTML page. Because V8 is shared across Chromium-based browsers, the flaw affects Google Chrome, Microsoft Edge, Opera, and other Chromium derivatives, not just Chrome itself. Successful exploitation gives an attacker code execution within the browser process on the victim's machine, a common foothold for delivering further malware. Google patched the bug in Chrome 116.0.5845.179/.180 (September 2023); any Chromium-based browser built on unpatched V8 remains vulnerable, and no public proof-of-concept is known. CISA added CVE-2023-4762 to the Known Exploited Vulnerabilities catalog on 2024-02-06, confirming exploitation in the wild (ransomware use unconfirmed), and EPSS assigns a ~41% probability of exploitation within 30 days (99th percentile).

Do: Patch all Chromium-based browsers fleet-wide to Chrome 116.0.5845.179/.180 or later and each vendor's equivalent (current Edge, Opera, Brave, etc.), consistent with the CISA KEV required action to apply vendor mitigations or discontinue use. Verify Chromium/V8 browser versions in your endpoint inventory before and after rollout; since exploitation is triggered by a crafted web page, interim mitigations include restricting unpatched machines' browsing and warning users about unsolicited links.

CVE-2023-4863 is a heap-based buffer overflow (CWE-787) in the WebP image codec used by Google Chromium, allowing a remote attacker to write outside the intended bounds of allocated memory. It is triggered when a user visits a crafted HTML page containing malicious WebP image data, so no authentication or special privileges are required, only that the victim loads attacker-controlled content in an affected application. Successful exploitation gives the attacker an out-of-bounds memory write in the affected process, which can lead to application crashes or memory corruption with the potential for code execution. Exposure is unusually broad because, per the advisory, the flaw can affect any application that uses the WebP codec, meaning the browsing public and any software bundling WebP decoding are plausibly in scope. The flaw was added to the CISA KEV catalog on 2023-09-13, indicating confirmed exploitation in the wild; EPSS assigns it a 100% probability of exploitation within 30 days, ransomware use is unknown, and no public proof-of-concept is known.

Do: Update Google Chrome and all other Chromium-based browsers to the latest stable release containing the WebP fix (the patched Chrome 116.0.5845.187 shipped in September 2023), and update or rebuild any other software that bundles the WebP/libwebp codec (fixed in libwebp 1.3.2). Until patching is complete, treat untrusted web content as the attack vector and, per the CISA KEV required action, apply mitigations per vendor instructions or discontinue use of affected software if mitigations are unavailable. Verify remediation by checking installed browser and application versions against the vendor advisories.

CVE-2023-5217 is a heap buffer overflow (CWE-787) in the VP8 encoding path of libvpx, the open-source video codec library bundled with Google's Chromium/Chrome browser. A remote attacker can trigger the flaw by luring a user to a crafted HTML page whose web content invokes the vulnerable VP8 encoding code, corrupting the heap and potentially achieving code execution in the affected browser. Anyone running Google Chrome/Chromium — or other browsers and software that embed libvpx, as CISA notes the library's use is 'not limited to Google Chrome' — is affected. Exploitation is confirmed: CISA added the flaw to the Known Exploited Vulnerabilities catalog on 2023-10-02 (ransomware association: unknown), though no public proof-of-concept is available and a CVSS score has not been published; EPSS puts the 30-day exploitation probability at 49% (99th percentile). Defenders should treat this as an actively exploited browser vulnerability requiring prompt patching.

Do: Update Chrome/Chromium to the vendor release that fixes CVE-2023-5217 — Google shipped the fix with its late-September 2023 stable-channel security update, so verify the exact build number in Google's advisory (it is not specified in the source data). Also patch any other products bundling libvpx (other browsers, media/ffmpeg-based tooling) per vendor instructions, and ensure KEV compliance by applying the required mitigations or discontinuing use of affected builds by the CISA deadline.

CVE-2023-6345 is an integer overflow (CWE-190) in Skia, the 2D graphics rendering library used by Google Chrome and other Chromium-based browsers. It is triggered when a compromised renderer processes a malicious file, allowing a remote attacker who has already gained code execution in the renderer process to escape the Chrome sandbox and run code with broader privileges. Users of Google Chrome prior to 119.0.6045.199 are affected, as are Chromium-based derivatives including Microsoft Edge (Chromium) and Chromium packages shipped by Debian and Fedora. The flaw was rated High by Chromium, carries a CVSS 3.1 score of 9.6, and was added to CISA's Known Exploited Vulnerabilities catalog on 2023-11-30. Google has patched the bug in Chrome 119.0.6045.199, and news reporting confirms it was being actively exploited in the wild at the time of the fix.

Do: Update Google Chrome to 119.0.6045.199 or later and restart the browser to fully apply the fix; on Debian and Fedora, apply the updated chromium packages from the distro repositories, and allow Microsoft's Chromium fix to flow into Edge before trusting affected builds. Verify browser versions (chrome://version or equivalent) across managed fleets, and note that because this is CISA KEV-listed (added 2023-11-30), US federal agencies must patch per vendor instructions or discontinue use by the required deadline.