CVE-2025-62593: Ray AI Compute Engine RCE Vulnerability

CVE-2025-62593 Overview

CVE-2025-62593 is a critical Remote Code Execution (RCE) vulnerability affecting Ray, an AI compute engine widely used by developers for machine learning and distributed computing workloads. The vulnerability allows attackers to execute arbitrary code on systems running Ray versions prior to 2.52.0 through a sophisticated browser-based attack chain combining User-Agent header spoofing with DNS rebinding techniques.

Developers using Ray as a development tool can be exploited when visiting a malicious website or being served a malicious advertisement (malvertising). The attack specifically targets Firefox and Safari browsers due to the insufficient security guard implemented in Ray's defense mechanism.

Critical Impact

Attackers can achieve full remote code execution on developer workstations running Ray, potentially compromising AI/ML development environments, accessing sensitive training data, and pivoting to internal infrastructure.

Affected Products

• Ray versions prior to 2.52.0
• Development environments using Ray with Firefox browser
• Development environments using Ray with Safari browser

Discovery Timeline

• 2025-11-26 - CVE-2025-62593 published to NVD
• 2025-12-01 - Last updated in NVD database

Technical Details for CVE-2025-62593

Vulnerability Analysis

This vulnerability is classified as CWE-94 (Improper Control of Generation of Code), commonly known as Code Injection. The flaw exists in Ray's browser-based attack prevention mechanism, which relies on checking if the User-Agent header starts with the string "Mozilla" to distinguish between legitimate API calls and browser-initiated requests.

This defense mechanism is fundamentally flawed because the Fetch specification allows the User-Agent header to be modified by JavaScript code in certain contexts. When combined with a DNS rebinding attack, an attacker can bypass this protection entirely and execute arbitrary code on the target system.

The attack requires user interaction in the form of visiting a malicious webpage, but this can be achieved through various social engineering vectors including malvertising campaigns that serve malicious ads on legitimate websites.

Root Cause

The root cause of this vulnerability is an insufficient security control that relies on client-controllable data (the User-Agent header) to make security decisions. The assumption that browser requests will always contain a User-Agent header starting with "Mozilla" is incorrect, as:

1. The Fetch API allows modification of the User-Agent header in certain scenarios
2. DNS rebinding attacks can cause the browser's same-origin policy to be bypassed
3. The combination of these two techniques enables an attacker to craft requests that appear to come from a legitimate client while actually originating from a malicious webpage

Attack Vector

The attack leverages a network-based vector requiring user interaction. The exploitation chain works as follows:

1. The victim visits a malicious website or is served a malicious advertisement
2. The attacker's JavaScript initiates a DNS rebinding attack, causing the malicious domain to resolve to the victim's localhost or internal Ray service
3. Once the DNS rebinding succeeds, the attacker's script can make requests to the Ray service
4. By manipulating the User-Agent header to bypass the "Mozilla" check, the attacker can access Ray's API endpoints
5. The attacker then executes arbitrary code through Ray's execution capabilities

For detailed technical information about the vulnerability mechanism and exploitation, refer to the GitHub Security Advisory GHSA-q279-jhrf-cc6v.

Detection Methods for CVE-2025-62593

Indicators of Compromise

• Unusual network connections from Ray services to external domains
• Ray API calls originating from browser processes with modified User-Agent headers
• Unexpected code execution or process spawning from Ray worker processes
• DNS queries showing signs of rebinding attacks (rapid TTL changes, multiple IP resolutions)

Detection Strategies

• Monitor Ray service logs for API requests with non-standard or modified User-Agent headers
• Implement network monitoring to detect DNS rebinding attack patterns
• Deploy endpoint detection rules to identify unexpected child processes spawned by Ray workers
• Review browser network activity for connections to localhost Ray services from external page contexts

Monitoring Recommendations

• Enable verbose logging on Ray dashboard and API services
• Implement DNS monitoring to detect rapid DNS resolution changes indicative of rebinding attacks
• Configure SIEM alerts for unusual Ray service activity patterns
• Monitor for connections to Ray services from untrusted network contexts

How to Mitigate CVE-2025-62593

Immediate Actions Required

• Upgrade Ray to version 2.52.0 or later immediately
• Restrict network access to Ray services to trusted IP ranges only
• Implement additional authentication mechanisms for Ray API endpoints
• Educate developers about the risks of visiting untrusted websites while running Ray services

Patch Information

The vulnerability has been patched in Ray version 2.52.0. The fix implements more robust browser-based attack prevention that does not rely solely on User-Agent header inspection. Organizations should upgrade to the patched version as soon as possible.

The patch commit can be reviewed at the GitHub Commit Update.

Workarounds

• Bind Ray services to localhost only and avoid exposing them on network interfaces
• Use a firewall to restrict access to Ray ports from external networks
• Run Ray in isolated network environments or containers with restricted network access
• Consider using browser extensions that prevent DNS rebinding attacks
• Avoid running Ray services while browsing untrusted websites

# Configuration example: Restrict Ray to localhost only
# When starting Ray, bind to localhost to prevent external access
ray start --head --dashboard-host=127.0.0.1 --node-ip-address=127.0.0.1

# Alternatively, use firewall rules to restrict Ray port access
# Example using iptables to block external access to Ray dashboard (default port 8265)
iptables -A INPUT -p tcp --dport 8265 -s 127.0.0.1 -j ACCEPT
iptables -A INPUT -p tcp --dport 8265 -j DROP