CVE-2025-62593

Ray, the open-source AI compute engine, is vulnerable to a critical remote code execution flaw (CVE-2025-62593, CWE-94/CWE-352) in versions prior to 2.52.0, caused by an insufficient guard against browser-based attacks: the software distinguishes browser traffic only by checking that the User-Agent header starts with 'Mozilla', but the fetch specification allows that header to be modified. An attacker can combine DNS rebinding with a crafted User-Agent so that a developer's Firefox or Safari browser silently sends malicious requests to locally running Ray services after the developer visits an attacker-controlled website or is served a malicious advertisement (malvertising). Successful exploitation yields full remote code execution on the machine running Ray, with high confidentiality, integrity and availability impact reflected in the CVSS 4.0 score of 9.4. Affected users are developers running Ray as a development tool on any version before 2.52.0, which is the fixed release. The flaw is being actively exploited in the wild: CISA added it to the Known Exploited Vulnerabilities catalog on 2026-08-17, a public proof of concept is available in the project's GitHub security advisory (GHSA-q279-jhrf-cc6v), and EPSS estimates a 16.9% probability of exploitation in the next 30 days.

What to do: Upgrade Ray to version 2.52.0 or later immediately, in line with CISA KEV and BOD 26-04 patching requirements. Until patched, avoid browsing untrusted websites (including ad-serving pages) while Ray development services are running, and restrict network access to locally running Ray services. Focus triage on machines where developers use Firefox or Safari alongside Ray, and hunt for signs of compromise since the flaw is actively exploited.