Microsoft Edge (Chromium-based): Use-after-free allows privilege escalation
Summary
A use-after-free vulnerability (CWE-416) in Microsoft Edge (Chromium-based) allows an unauthorized attacker to elevate privileges over the network, according to the CNA record. The attack requires user interaction, for example opening a malicious web page. The CVSS 3.1 base score is 8.8 (High), and NVD analysis is still pending.
Affected
- Microsoft Edge (Chromium-based) from 1.0.0.0 up to, but not including, 155.0.4283.45 (CNA record)
Fixed in
- Microsoft Edge (Chromium-based) 155.0.4283.45 (fixed build according to the CNA record and OffSeq/Strix)
- Microsoft's advisory was not checked for the fixed build; verify it before using it as a patch baseline.
- Install the current Edge Stable build, which is newer than 155.0.4283.45.
Workaround
Unknown. No workaround was identified; apply the update.
Exploitation
- No evidence of exploitation in the wild was found (OffSeq).
- Not listed in CISA KEV according to an automated GitHub alert; the CISA catalogue was not checked directly.
- No public proof of concept was found.
- CISA SSVC assessment: Exploitation none, Automatable no, Technical Impact total.
Our recommendation
- Update Edge to the current Stable build on all Windows endpoints and verify the installed version.
- Start with users who browse untrusted websites.
- Read Microsoft's known-issues page before forcing the Edge 155 rollout on machines with existing profiles.
- Keep Edge auto-update active or enforce updates centrally through Intune or Group Policy.
- Recheck the MSRC advisory and NVD in a few days.
Information from Microsoft (Patch Tuesday October 2026)
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Update Guide: CVE-2026-96203 msrc.microsoft.com
- Microsoft Edge Stable channel release notes learn.microsoft.com
- Microsoft Edge known issues learn.microsoft.com
- Microsoft Edge 155 release notes learn.microsoft.com
- VulDB: vuln 428583 vuldb.com
- OffSeq Radar: CVE-2026-96203 radar.offseq.com
- Strix: CVE-2026-96203 www.strix.ai
- PSIRT: CVE-2026-96203 psirt.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, 09:01.
Original description (NVD)
Use after free in Microsoft Edge (Chromium-based) allows an unauthorized attacker to elevate privileges over a network.
NVD references (1)
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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