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CVE-2021-47936

9.3
Critical
EPSS 0.66%May 10, 2026

OpenCATS 0.9.4 RCE via unauthenticated upload.

common questions

Is CVE-2021-47936 being exploited?

Not confirmed. CVE-2021-47936 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.66% probability of exploitation in the next 30 days.

How severe is CVE-2021-47936?

CVE-2021-47936 is rated Critical with a CVSS score of 9.3. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.

Is there a patch for CVE-2021-47936?

Not known from our data. No patch reference has been recorded for CVE-2021-47936, which is not the same as no patch existing — a fix may have shipped without a tagged reference, or after this record was written. The vendor advisory is the only authority on whether a fix exists, and mitigations may be available regardless.

What does CVE-2021-47936 affect?

CVE-2021-47936 affects OpenCATS 0.9.4. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.

What should I do about CVE-2021-47936?

Patch when available; enforce strict upload validation and sandboxing

Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.

executive summary
technical analysis
affected
OpenCATS 0.9.4
impact

RCE via unauthenticated PHP upload to careers endpoint; attacker runs commands on server, full compromise risk.

action required

Patch when possible

affected versions
Opencats OpenCATS
  • affected<= 0.9.4

As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.

how to fix
Remediation steps are tailored for users whose stack is affected. Add this technology to your stack to see the fix checklist.
references
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