HOMEVULNERABILITIESCVE-2021-47936
CRITICAL

CVE-2021-47936

CWE-306Published: May 10, 2026· Updated: May 12, 2026

9.8
CVSS v3.1
EPSS:0.22%probability of exploitation in 30 daysPercentile:44.9th

Official 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.

NVD Source

Technical Analysis

CVE-2021-47936 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 9.8.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected Vendors & Products

Mentioned vendors (from description):
PHP
CPE data not yet available in NVD for this CVE.

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

All References (4)

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

Quick Facts

CVE IDCVE-2021-47936
CVSS Score9.8 / 10
SeverityCRITICAL
WeaknessCWE-306
CISA KEVNo
EPSS (30d)0.22%
PublishedMay 10, 2026

Related CVEs (CWE-306)

CVE-2026-54309
10.0
CVE-2026-20223
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CVE-2026-44329
10.0
CVE-2026-34162
10.0
CVE-2026-49257
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CVE-2026-46803
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Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2021-47936 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.
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