CVE-2026-87515 Overview
CVE-2026-87515 is an incorrect authorization vulnerability [CWE-863] in the FileAPI component of Google Chrome. The flaw affects Chrome versions prior to 153.0.8010.36. A remote attacker can bypass system access restrictions by serving a crafted HTML page and convincing the user to interact with it. Google classifies the Chromium security severity as Medium.
The vulnerability requires user interaction and social engineering. Successful exploitation compromises integrity of resources that FileAPI normally gates behind authorization checks. Google addressed the issue in the stable channel update tracked as Chromium Issue #497093426.
Critical Impact
Remote attackers can bypass FileAPI access restrictions through a crafted HTML page, enabling unauthorized interaction with local file resources when a user is lured to a malicious site.
Affected Products
- Google Chrome for Desktop prior to 153.0.8010.36
- Chromium-based browsers incorporating the vulnerable FileAPI implementation
- Downstream distributions that had not yet merged the upstream fix
Discovery Timeline
- 2026-09-09 - CVE-2026-87515 published to NVD
- 2026-09-10 - Last updated in NVD database
- Google released the fix via the Stable Channel Update for Desktop
Technical Details for CVE-2026-87515
Vulnerability Analysis
The defect lives in Chrome's FileAPI, the browser subsystem that exposes File, Blob, and FileReader interfaces to web content. FileAPI enforces authorization to prevent web origins from reaching files or system resources they should not touch. In vulnerable builds, that authorization check is incorrect, allowing a crafted page to reach protected resources.
Exploitation is remote over the network and requires the victim to visit an attacker-controlled page. The CVSS vector highlights an integrity impact without direct confidentiality or availability effects, meaning the attacker can influence protected state rather than exfiltrate arbitrary secrets or crash the browser. The reported EPSS probability is 0.247%.
Root Cause
The root cause is an improper authorization decision inside FileAPI logic, mapped to [CWE-863]. Rather than failing closed when a request should be denied, the affected code path permits an action that policy should reject. Google has not published low-level details in the public advisory, and the tracking issue Chromium Issue #497093426 remains restricted.
Attack Vector
An attacker hosts a malicious HTML page and drives a target to open it through phishing, malvertising, or a compromised site. The page issues FileAPI operations that the browser should refuse but instead allows. No privileges are required on the target system, and no credentials are needed beyond the victim rendering the page. Verified public proof-of-concept code is not available at time of writing.
See the Google Chrome Stable Update advisory for the vendor's release notes.
Detection Methods for CVE-2026-87515
Indicators of Compromise
- Browser telemetry showing Chrome desktop versions below 153.0.8010.36 still active in the environment
- Web proxy or DNS logs recording user navigation to newly registered or low-reputation domains serving HTML that invokes Blob, File, or FileReader APIs
- Endpoint logs showing unexpected browser child processes or file access following a browsing session to an untrusted origin
Detection Strategies
- Inventory installed Chrome versions across managed endpoints and flag any build prior to 153.0.8010.36
- Alert on outbound requests to URLs delivered through phishing campaigns that reference FileAPI-heavy JavaScript payloads
- Correlate browser process activity with file system access events to identify anomalous reads or writes originating from a browser tab
Monitoring Recommendations
- Ingest browser update state and process telemetry into a centralized data lake for version compliance reporting
- Monitor phishing and secure email gateway feeds for lures that direct users to attacker-hosted HTML content
- Track social-engineering indicators such as spoofed login prompts or file-download instructions delivered from unmanaged domains
How to Mitigate CVE-2026-87515
Immediate Actions Required
- Update Google Chrome to 153.0.8010.36 or later on all Windows, macOS, and Linux endpoints
- Restart Chrome after applying the update so the patched binaries load in every user session
- Reinforce user awareness on social-engineering lures that direct victims to open unfamiliar HTML pages
Patch Information
Google addressed CVE-2026-87515 in the Chrome stable channel release documented in the Stable Channel Update for Desktop. Administrators should confirm managed installations report version 153.0.8010.36 or newer. Chromium-derived browsers should be updated once their maintainers ship a build that incorporates the upstream fix referenced in Chromium Issue #497093426.
Workarounds
- Enforce automatic Chrome updates through group policy or MDM to eliminate stale versions
- Restrict browsing to trusted origins using URL filtering while patching is in progress
- Apply browser isolation or sandboxing for high-risk user populations that routinely receive external links
# Verify installed Chrome version on Linux/macOS endpoints
google-chrome --version
# Expected output should be 153.0.8010.36 or later
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.