Arbitrary remote file read in Wrangler dev serverGHSA-cfph-4qqh-w828
MEDIUMFix: cloudflare/workers-sdk#4532GHSA-cfph-4qqh-w828 is a medium-severity (CVSS 6.9) Improper Authentication vulnerability in wrangler. A fix is available for wrangler — see the affected versions and patch details below.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
wranglernpmDescription
Impact
Sending specially crafted HTTP requests and inspector messages to Wrangler's dev server could result in any file on the user's computer being accessible over the local network. An attacker that could trick any user on the local network into opening a malicious website could also read any file.
Patches
This issue was fixed in [email protected]. Wrangler will now only serve files that are part of your bundle, or referenced by your bundle's source maps.
Workarounds
Configure Wrangler to listen on local interfaces instead with wrangler dev --ip 127.0.0.1. This is the default as of [email protected], and removes the local network as an attack vector, but does not prevent an attack from visiting a malicious website.
References
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | wrangler | ≥ 3.9.0&&< 3.19.0 | 3.19.0npm install wrangler@3.19.0 |
Affected Products
wranglercloudflareDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for wrangler, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update wrangler to 3.19.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-cfph-4qqh-w828 is resolved across your whole dependency graph.
Workarounds
Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.
Frequently Asked Questions
Is GHSA-cfph-4qqh-w828 in your dependencies?
Find it across npm, including transitive dependencies.