CVE-2026-106300 Overview
CVE-2026-106300 is a race condition vulnerability in the CacheStorage component of Google Chrome. The flaw affects Chrome versions prior to 155.0.8059.39 and is tracked under [CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition]. A remote attacker who has already compromised the renderer process can exploit this flaw through a crafted HTML page to read memory outside the Chrome sandbox. Google classified the Chromium security severity as Medium.
Critical Impact
Attackers with renderer compromise can read process memory outside the sandbox boundary, enabling information disclosure that may support broader exploit chains.
Affected Products
- Google Chrome versions prior to 155.0.8059.39
- Chromium-based browsers using the vulnerable CacheStorage implementation
- Desktop builds across supported platforms per the Chrome Stable channel update
Discovery Timeline
- 2026-10-06 - CVE-2026-106300 published to the National Vulnerability Database (NVD)
- 2026-10-07 - Last updated in NVD database
Technical Details for CVE-2026-106300
Vulnerability Analysis
The vulnerability resides in Chrome's CacheStorage, the browser subsystem that backs the Service Worker Cache API. CacheStorage operates across the renderer and browser processes, exchanging references to cached response bodies through inter-process communication (IPC). The race condition arises when the state of a cache entry changes between validation and use. An attacker who already controls the renderer process can time operations against CacheStorage to read memory contents that should remain isolated by the sandbox. The result is cross-boundary information disclosure limited to confidentiality impact, with no direct integrity or availability effect.
Root Cause
The root cause is a classic time-of-check to time-of-use (TOCTOU) flaw [CWE-367]. The CacheStorage code path validates an object or buffer state at one moment but accesses the resource at a later moment without re-validation. A concurrent thread or IPC message can mutate the state in that window, causing the accessor to read from memory that no longer corresponds to the validated object. Technical details are tracked in Chromium Issue Tracker #500106110.
Attack Vector
Exploitation requires two conditions. The attacker must first compromise the renderer process, typically by chaining a separate renderer bug delivered through a crafted HTML page. With renderer control, the attacker then issues timed CacheStorage operations to trigger the race and read memory outside the sandbox. User interaction is required to load the attacker-controlled page. The flaw is not a standalone sandbox escape, but it provides the information disclosure primitive that often supports one.
Detection Methods for CVE-2026-106300
Indicators of Compromise
- Chrome renderer processes exhibiting repeated or anomalous CacheStorage IPC traffic preceding crashes or unexpected memory access patterns.
- Browser crash reports referencing content::CacheStorage or Service Worker cache code paths.
- Outbound connections from endpoints to pages that embed unusual Service Worker registrations followed by rapid cache operations.
Detection Strategies
- Inventory Chrome versions across the fleet and flag any instance below 155.0.8059.39.
- Correlate browser crash telemetry with URL navigation history to identify renderer compromise attempts.
- Monitor for process behavior consistent with sandbox escape chains, such as renderer processes spawning unexpected children.
Monitoring Recommendations
- Collect Chrome crash dumps centrally and alert on signatures tied to CacheStorage or Service Worker modules.
- Ingest browser process telemetry into a security data lake for retrospective hunting against newly published indicators.
- Track Chrome auto-update success rates to confirm patched versions are deployed on managed endpoints.
How to Mitigate CVE-2026-106300
Immediate Actions Required
- Update Google Chrome to version 155.0.8059.39 or later on all managed endpoints.
- Restart Chrome after the update to ensure the patched binary is loaded in all running sessions.
- Validate update deployment through endpoint management reporting and version inventories.
Patch Information
Google released the fix in the Chrome Stable channel update documented in the Google Chrome Stable Release Update. Chromium downstream vendors should pick up the corresponding commit referenced in Chromium Issue Tracker #500106110 and ship updated builds. Enterprise administrators using Chrome Browser Enterprise should confirm that update policies allow timely rollout of the patched version.
Workarounds
- Enforce site isolation and strict Cross-Origin-Opener-Policy and Cross-Origin-Embedder-Policy headers to reduce renderer compromise exposure.
- Restrict installation of untrusted browser extensions that could expand the attack surface of the renderer process.
- Use enterprise policies to block navigation to high-risk categories until Chrome is updated across the environment.
# Verify installed Chrome version on Linux endpoints
google-chrome --version
# Example Windows registry policy to force auto-update
reg add "HKLM\SOFTWARE\Policies\Google\Update" /v UpdateDefault /t REG_DWORD /d 1 /f
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
