CISA Adds Actively Exploited Ray Flaw to KEV Catalog: Browser-Based RCE via DNS Rebinding

The U.S. Cybersecurity and Infrastructure Security Agency (CISA) has added a critical vulnerability in Ray, an open-source Python-native distributed computing framework, to its Known Exploited Vulnerabilities (KEV) catalog, citing active exploitation. The flaw, tracked as CVE-2025-62593 (CVSS 9.4), allows remote code execution (RCE) through web browsers like Mozilla Firefox and Apple Safari via a DNS rebinding attack.

Ray is widely used for scaling AI and machine learning workloads, with over 43,500 GitHub stars. The vulnerability stems from the Ray Development team’s longstanding decision not to implement authentication on critical endpoints such as /api/jobs and /api/job_agent/jobs/. Combined with insufficient controls against browser-based attacks—specifically scenarios where the User-Agent header can be modified—attackers can exploit a developer who visits a malicious website or is served a malicious advertisement. The attack can also be extended to network-adjacent Ray instances by using the browser as a confused deputy intermediary to target instances inside a private corporate network.

The issue primarily impacts developers running development/testing environments. Successful exploitation can lead to arbitrary shell code execution on the victim’s machine. The flaw has been patched in Ray version 2.52.0. The vulnerability was discovered by Oligo security researcher Avi Lumelsky, with Jonathan Leitschuh credited for the DNS rebinding attack.

CISA has not disclosed specific exploitation details, but a BitSight report from March 2026 revealed that threat actors behind the RondoDox DDoS botnet incorporated the vulnerability into their arsenal two days before public disclosure on November 26, 2025, due to the availability of a proof-of-concept exploit. Additionally, Oligo reported that unpatched Ray instances have been targeted in campaigns like ShadowRay 2.0, which aims to turn infected clusters with NVIDIA GPUs into a self-replicating cryptocurrency mining botnet.

Federal Civilian Executive Branch (FCEB) agencies are required to apply fixes and mitigations by August 20, 2026.