Google Chrome: Web origin policy bypass in Forms component
Summary
Google Chrome versions before 156.0.8078.73 contain an improper access control flaw in the Forms component that allows a remote attacker to bypass the web origin policy. The attacker must lure a user to a crafted HTML page, so user interaction is required. Successful exploitation can expose data and sessions on other websites the user is logged into. Chromium rates the flaw High, and the CVE record reports partial confidentiality and integrity impact with no availability impact.
Affected
- Google Chrome (desktop) prior to 156.0.8078.73
- Linux distribution packages are tracked separately (Ubuntu lists chromium-browser as not affected because it installs the Chromium snap)
Fixed in
- Google Chrome 156.0.8078.73 (Linux) and 156.0.8078.73/.74 (Windows, macOS), according to secondary reports of Google's Stable update of 27 October 2026. Verify against Google's advisory.
- Debian: Chromium update DSA 6592-1; check the Debian security page for the package version.
Workaround
Unknown. No vendor workaround is documented. Apply the update.
Exploitation
- No evidence of exploitation in the wild was found.
- A third-party tracker reports the CVE is not listed in CISA KEV; this was not verified against the KEV catalogue.
- No public proof-of-concept was found. Because the check was made before publication, this is limited evidence.
Our recommendation
- Update Chrome to the fixed version on all endpoints and restart the browser.
- Check Chrome versions on managed devices and confirm that auto-update is not blocked by policy.
- Check Linux hosts using Debian or Ubuntu packages separately.
- Monitor for changes in exploitation status.
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Chrome Releases: Stable Channel Update for Desktop chromereleases.googleblog.com
- Chromium issue tracker entry issues.chromium.org
- Ubuntu security: CVE-2026-118337 ubuntu.com
- Red Hat CVE entry via Vulners (Debian DSA 6592-1 reference) vulners.com
- VulDB: CVE-2026-118337 vuldb.com
- OffSeq radar: CVE-2026-118337 radar.offseq.com
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 31 Oct 2026, 00:33.
Original description (NVD)
Improper access control in Forms in Google Chrome prior to 156.0.8078.73 allowed a remote attacker to bypass web origin policy via a crafted HTML page. (Chromium security severity: High)
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
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