CVE-2026-76026: The Chrome Autofill Flaw Behind Sandboxed RCE

A routine update, a serious flaw

On October 29, 2026, Google announced a Chrome desktop update containing 21 security fixes. Among them was a high-severity issue in Autofill: CVE-2026-76026. Google release announcement

The CVE record appeared the following day. It describes an attack in which a specially crafted HTML page could trigger arbitrary code execution inside Chrome’s sandbox on affected versions. CVE record

That qualification matters. The disclosed impact is sandboxed code execution—not a demonstrated escape into the operating system. It is a serious browser vulnerability, but describing it as a confirmed full-device takeover would go beyond the published evidence. CVE description, Chrome security architecture

What the vulnerability does

The affected component is Chrome Autofill. Google classifies the flaw as memory corruption, rates it High, and identifies Chrome versions before 156.0.8078.79 as affected. The stated attack input is a crafted HTML page. Google release announcement, CVE record

The published weakness identifier is CWE-119, a broad category concerning operations outside the intended bounds of a memory buffer. That classification alone does not establish a specific out-of-bounds write, use-after-free, or other precise root cause. MITRE CWE-119

In plain language, malicious web content can exploit a memory-safety defect to make a vulnerable browser process execute attacker-controlled code, subject to its sandbox restrictions. The advisory does not establish that victims must submit an Autofill form, save payment details, or click an Autofill suggestion. CVE description

The disclosure timeline

The available history documents reporting, patching, and publication—not a confirmed attack campaign.

Date	Verified development
September 29, 2026	Google’s release notes credit Google with reporting the Autofill vulnerability; no individual researcher is named.
October 29, 2026	Google announces the repaired Stable and Extended Stable desktop releases as part of a 21-fix update.
October 30, 2026	The CVE is published, describing arbitrary code execution inside the sandbox.
October 30, 2026	CISA ADP Vulnrichment adds a CVSS 3.1 assessment of 8.8 High.

Timeline sources: Google release announcement, official CVE JSON.

The September date is the reported date, not a verified date of first discovery or exploitation. The October 29 patch announcement and October 30 CVE publication are separate events. Google release announcement, CVE record

Why the sandbox boundary matters

Chrome uses sandboxing to restrict compromised processes’ access to local resources, including arbitrary files and devices. Site Isolation provides another defensive boundary intended to protect other websites’ data when a renderer is compromised. Chromium Site Isolation documentation

These protections do not make arbitrary code execution harmless. They do mean this CVE should not automatically be labelled an operating-system compromise or local privilege-escalation vulnerability. A claim of sandbox escape would need evidence of an additional weakness, exploit chain, or containment failure; that evidence is not supplied by this CVE’s description. CVE description, Chromium security architecture

Severity and attack requirements

The CVSS 3.1 base score is 8.8 High, with vector:

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

The CVE record attributes this numerical assessment to CISA ADP Vulnrichment. Google separately supplies the Chromium severity label High, not a numerical score. Official CVE JSON, Tenable CVE entry, Google release announcement

Assessment element	What it means
Network attack vector	The scoring model permits remotely supplied content.
Low attack complexity	The base assessment assigns low complexity; this does not guarantee an available, reliable public exploit.
No privileges required	The attacker needs no prior privileges under the model.
User interaction required	The assessment requires victim interaction; it is not a zero-click classification.
Scope unchanged	The score does not establish a sandbox escape.

Source: CVSS assessment in the official CVE JSON.

The supported exposure scenario is a user encountering crafted HTML in a vulnerable browser. Phishing is one conceivable delivery method, but the advisory does not attribute this flaw to a specific phishing operation. CVE description

Is there a confirmed incident?

As of October 30, the reviewed Google release notice does not announce in-the-wild exploitation of CVE-2026-76026. The checked CISA KEV dataset contains no entry for this CVE, and the CVE record’s CISA SSVC assessment records exploitation as none. These observations do not prove exploitation cannot occur or has never occurred. Google release announcement, CISA KEV dataset, official CVE JSON

No confirmed victim, named threat actor, or verified public exploit was identified in the reviewed sources. The accurate story is a newly disclosed, patched browser vulnerability—not a documented breach or confirmed zero-day campaign. Google release announcement, CVE entry

The October 30 EPSS value is 0.00198, or 0.198%. FIRST defines EPSS as an estimate of observed exploitation activity over the next 30 days—not a reader’s individual probability of compromise. A low value is not a reason to disregard a high-severity browser patch. Dated FIRST API result, FIRST explanation

Which versions need updating?

The published desktop affected boundary is Chrome before 156.0.8078.79. The repaired releases are listed below. CVE description, HKCERT bulletin

Platform	Fixed release announced
Windows	156.0.8078.79 or 156.0.8078.80
macOS	156.0.8078.79 or 156.0.8078.80
Linux	156.0.8078.79
Android	156.0.8078.79; Google states corresponding Android releases contain desktop security fixes unless otherwise noted.

Sources: Google October release archive, HKCERT bulletin.

Install the latest supported stable update offered for the platform rather than targeting an old minimum fixed build. Do not apply these desktop version numbers indiscriminately to ChromeOS, iOS, or other Chromium-based browsers; check their own update paths and product advisories. Google update instructions, iOS update instructions

How to apply the fix

1. Open the update screen: Chrome menu → Help → About Google Chrome. Chrome checks for updates on that page.
2. Install and relaunch: Select Relaunch when offered. A downloaded update takes effect when the browser restarts.
3. Verify the running version: Return to the About screen and confirm the applicable repaired build or a later supported stable release.
4. Use platform updates: On Linux, use the package manager; on Android, update Chrome through Google Play.

Sources: Google desktop instructions, Google Android instructions.

For organizations, a practical completion check is the version running after relaunch, not merely a successful download. Google’s release announcement describes a staged rollout over days or weeks, so announcement day does not mean every device is already protected. Update instructions, release announcement

What not to treat as protection

Disabling Autofill is not a verified workaround in the reviewed Google advisory or CVE description. Do not present that setting change, the absence of saved payment cards, or trusted-site-only browsing as substitutes for installing the patch. Google release announcement, CVE record

The reviewed public material provides no CVE-specific indicators of compromise. A crash alone should therefore not be attributed to exploitation of this flaw. If other evidence suggests compromise, preserve relevant browser and endpoint telemetry and follow the organization’s incident-response process. Google release announcement, CVE entry

Reader questions

Does this automatically take over the computer? No. The published impact is code execution inside Chrome’s sandbox, not demonstrated host takeover. CVE description

Does the attacker need an account? The assessment lists no privileges required, but user interaction is required. CVSS information

Is 156.0.8078.79 vulnerable? The description says versions prior to that build are affected; Google lists .79/.80 as the repaired desktop release. CVE record, release announcement

Is it actively exploited? The reviewed official notice does not announce active exploitation, and no confirmed campaign was identified in the sources reviewed as of October 30. Absence of confirmation is not proof of safety. Google release announcement, CISA assessment

Last reviewed: October 30, 2026.

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