CVE-2025-12419 — AI Deep Analysis Summary

Q: What is this vulnerability? (Essence + Consequences)

🚨 **Essence**: Mattermost OAuth state token validation is insufficient. 💥 **Consequences**: Attackers can hijack user accounts. 📉 **Impact**: Full compromise of user identity and session integrity.

Q: Root Cause? (CWE/Flaw)

🛡️ **CWE**: CWE-303 (Improper Authentication). 🔍 **Flaw**: The system fails to properly verify OAuth state tokens during the authentication flow.

Q: Who is affected? (Versions/Components)

📦 **Affected Versions**: • 10.12.x (≤ 10.12.1) • 10.11.x (≤ 10.11.4) • 10.5.x (≤ 10.5.12) • 11.0.x (≤ 11.0.3)

Q: What can hackers do? (Privileges/Data)

🕵️ **Attacker Action**: Account Takeover (ATO). 🔑 **Privileges**: Gain full access to the victim's Mattermost account. 📂 **Data**: Read/write messages, access private channels, impersonate user.

Q: Is there a public Exp? (PoC/Wild Exploitation)

🚫 **Public Exploit**: No PoC or wild exploitation reported yet. 📅 **Status**: New vulnerability (Published 2025-11-27). ⏳ **Risk**: High potential for future exploits.

Q: How to self-check? (Features/Scanning)

🔍 **Check**: Verify your Mattermost version against the list above. 📡 **Scan**: Look for OAuth state token validation errors in logs. 👀 **Monitor**: Unusual login locations or session hijacking attempts.

Q: Is it fixed officially? (Patch/Mitigation)

✅ **Fix Available**: Yes. 🔧 **Action**: Upgrade to the latest patched versions immediately. 🔗 **Source**: Official Mattermost security updates page.

Q: What if no patch? (Workaround)

🛑 **Workaround**: Disable OAuth login methods temporarily if possible. 🔒 **Mitigation**: Enforce strict session monitoring and MFA. 🚧 **Limit**: No perfect workaround; patching is the only true fix.

Q: Is it urgent? (Priority Suggestion)

🔥 **Priority**: HIGH. ⚡ **Urgency**: Critical due to Account Takeover risk. 🏃 **Action**: Patch immediately. CVSS Score indicates High Impact (C:H, I:H, A:H).

Updated May 06, 2026 CVSS 9.9 · Critical

This is a summary of the AI-generated 10-question deep analysis. The full version (longer answers, follow-up Q&A, related CVEs) requires login. Read the full analysis →

Q1What is this vulnerability? (Essence + Consequences)

🚨 **Essence**: Mattermost OAuth state token validation is insufficient. <br>💥 **Consequences**: Attackers can hijack user accounts. <br>📉 **Impact**: Full compromise of user identity and session integrity.

Q2Root Cause? (CWE/Flaw)

🛡️ **CWE**: CWE-303 (Improper Authentication). <br>🔍 **Flaw**: The system fails to properly verify OAuth state tokens during the authentication flow.

Q3Who is affected? (Versions/Components)

📦 **Affected Versions**: <br>• 10.12.x (≤ 10.12.1) <br>• 10.11.x (≤ 10.11.4) <br>• 10.5.x (≤ 10.5.12) <br>• 11.0.x (≤ 11.0.3)

Q4What can hackers do? (Privileges/Data)

🕵️ **Attacker Action**: Account Takeover (ATO). <br>🔑 **Privileges**: Gain full access to the victim's Mattermost account. <br>📂 **Data**: Read/write messages, access private channels, impersonate user.

Q5Is exploitation threshold high? (Auth/Config)

🔓 **Auth Required**: Yes, PR:L (Privileges Required: Low). <br>⚙️ **Config**: UI:N (User Interaction: None). <br>🌐 **Network**: AV:N (Attack Vector: Network). <br>⚠️ **Threshold**: Moderate.…

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Q6Is there a public Exp? (PoC/Wild Exploitation)

🚫 **Public Exploit**: No PoC or wild exploitation reported yet. <br>📅 **Status**: New vulnerability (Published 2025-11-27). <br>⏳ **Risk**: High potential for future exploits.

Q7How to self-check? (Features/Scanning)

🔍 **Check**: Verify your Mattermost version against the list above. <br>📡 **Scan**: Look for OAuth state token validation errors in logs. <br>👀 **Monitor**: Unusual login locations or session hijacking attempts.

Q8Is it fixed officially? (Patch/Mitigation)

✅ **Fix Available**: Yes. <br>🔧 **Action**: Upgrade to the latest patched versions immediately. <br>🔗 **Source**: Official Mattermost security updates page.

Q9What if no patch? (Workaround)

🛑 **Workaround**: Disable OAuth login methods temporarily if possible. <br>🔒 **Mitigation**: Enforce strict session monitoring and MFA. <br>🚧 **Limit**: No perfect workaround; patching is the only true fix.

Q10Is it urgent? (Priority Suggestion)

🔥 **Priority**: HIGH. <br>⚡ **Urgency**: Critical due to Account Takeover risk. <br>🏃 **Action**: Patch immediately. CVSS Score indicates High Impact (C:H, I:H, A:H).

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Vulnerability detail Full AI analysis (login) Mattermost CWE-303