Arbitrary remote code execution within `wrangler dev` Workers sandbox
Critical severity
GitHub Reviewed
Published
Dec 29, 2023
in
cloudflare/workers-sdk
•
Updated Jan 3, 2024
Package
Affected versions
>= 3.0.0, < 3.19.0
>= 2.0.0, < 2.20.2
Patched versions
3.19.0
2.20.2
Description
Published by the National Vulnerability Database
Dec 29, 2023
Published to the GitHub Advisory Database
Jan 3, 2024
Reviewed
Jan 3, 2024
Last updated
Jan 3, 2024
Credits
-
Lekensteyn Reporter
Impact
The V8 inspector intentionally allows arbitrary code execution within the Workers sandbox for debugging.
wrangler devwould previously start an inspector server listening on all network interfaces. This would allow an attacker on the local network to connect to the inspector and run arbitrary code. Additionally, the inspector server did not validateOrigin/Hostheaders, granting an attacker that can trick any user on the local network into opening a malicious website the ability to run code. Ifwrangler dev --remotewas being used, an attacker could access production resources if they were bound to the worker.Patches
This issue was fixed in
wrangler@3.19.0andwrangler@2.20.2. Whilstwrangler dev's inspector server listens on local interfaces by default as ofwrangler@3.16.0, an SSRF vulnerability inminiflareallowed access from the local network untilwrangler@3.18.0.wrangler@3.19.0andwrangler@2.20.2introduced validation for theOrigin/Hostheaders.Workarounds
Unfortunately, Wrangler doesn't provide any configuration for which host that inspector server should listen on. Please upgrade to at least
wrangler@3.16.0, and configure Wrangler to listen on local interfaces instead withwrangler dev --ip 127.0.0.1to prevent SSRF. This removes the local network as an attack vector, but does not prevent an attack from visiting a malicious website.References
References