Researcher Details Microsoft Edge Sandbox Escape Built from Logic Flaws
Summary
Orange Tsai detailed a non-memory-corruption chain using Edge logic flaws to achieve UXSS, escape the sandbox and execute code on Windows. Demonstrated at Pwn2Own Berlin, it was patched in Edge 148.0.3967.70; there is no evidence it was used against real users.
Key points
- Orange Tsai of DEVCORE demonstrated the chain at Pwn2Own Berlin in May; the exploit later won $175,000.
- A navigation-throttle logic flaw enabled universal cross-site scripting, while additional Edge weaknesses helped trigger the chain without a click.
- The chain used Edge’s Immersive Reader to escape the sandbox, then abused a diagnostic-log function to write an attacker-controlled file.
- It modified a protocol-handler configuration file and used a telnet:// link to launch an attacker-planted program from a user-writable folder.
- One step read the victim’s email address from assets.msn[.]com because of a misconfigured cross-origin setting.
- Microsoft fixed the Edge flaws in version 148.0.3967.70 on May 15; the article says there is no evidence the chain was used against real users.
Article Details
- Attack Vectors
- A malicious web page triggers a chain of Edge and Windows logic flaws, producing universal cross-site scripting that can run JavaScript on any website and bypass content security policy.
- The exploit uses Edge's conditional access navigation throttle and a second-window popup path to trigger navigation in the browser's own process without a click.
- Edge's Immersive Reader runs under a read:// address that was not barred from running scripts; the chain uses this to call an internal diagnostic-log function and write an attacker-chosen file anywhere on disk.
- The chain overwrites a configuration file controlling which websites may launch protocol handlers, restarts Edge, and launches a telnet:// link. Windows searches the system path and runs an attacker-planted copy from a folder writable by a low-privileged user.
- Defensive Notes
- Microsoft fixed the Edge bugs on May 15 in Edge Stable version 148.0.3967.70; updating Edge closes the chain.
- The article reports no evidence that the competition exploit was used against real users. It says up-to-date browsers are not at risk.
MITRE ATT&CK
T1059.007 · JavaScriptThe chain uses JavaScript to create a universal cross-site scripting primitive that can run on any website.T1189 · Drive-by CompromiseThe demonstrated chain begins when a victim visits a malicious web page that triggers Edge logic flaws.T1203 · Exploitation for Client ExecutionThe exploit uses Edge logic flaws to achieve code execution outside the browser sandbox.T1574.007 · Path Interception by PATH Environment VariableAfter launching a telnet:// link, Windows searches the system path and runs an attacker-planted copy from a low-privileged-user-writable folder.
CVE
CVE-2026-45492in Edge Stable version 148.0.3967.70. That release carried three Edge-specific fixes, tracked as CVE-2026-45492, CVE-2026-45494, and CVE-2026-45495. The first is recorded as a security feature bypass, and theCVE-2026-45494version 148.0.3967.70. That release carried three Edge-specific fixes, tracked as CVE-2026-45492, CVE-2026-45494, and CVE-2026-45495. The first is recorded as a security feature bypass, and the second as a spoofingCVE-2026-45495That release carried three Edge-specific fixes, tracked as CVE-2026-45492, CVE-2026-45494, and CVE-2026-45495. The first is recorded as a security feature bypass, and the second as a spoofing bug, both affecting
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EdgeA chain of logic flaws, with no memory corruption, can turn a malicious web page into code running on a Windows computer outside Microsoft Edge's sandbox, a security researcher has shown.Immersive Readeris still not in control of the computer. To escape the sandbox, Tsai used Edge's reading mode, Immersive Reader, which runs under a custom read:// address that Microsoft left off the list of pages barred fromMicrosoft WindowsA chain of logic flaws, with no memory corruption, can turn a malicious web page into code running on a Windows computer outside Microsoft Edge's sandbox, a security researcher has shown.