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CVE-2021-35211 — AI Deep Analysis Summary

CVSS 9.0 · Critical

Q1What is this vulnerability? (Essence + Consequences)

🚨 **Essence**: A critical buffer error in SolarWinds Serv-U FTP Server. 📉 **Consequences**: Memory corruption leading to **Arbitrary Code Execution** on the target system.…

Q2Root Cause? (CWE/Flaw)

🛠️ **Root Cause**: Boundary error leading to a **Buffer Overflow**. 💥 This allows attackers to write beyond memory limits, corrupting the server's memory state.

Q3Who is affected? (Versions/Components)

🏢 **Affected**: SolarWinds Serv-U Managed File Transfer Server & Serv-U Secured FTP. 📅 **Status**: Vulnerable versions prior to **15.2.3 HF2** are at risk.

Q4What can hackers do? (Privileges/Data)

💀 **Impact**: Full **Remote Code Execution (RCE)**. 🗝️ Attackers gain **privileged access**, allowing them to steal data, install backdoors, or take full control of the system.

Q5Is exploitation threshold high? (Auth/Config)

🔓 **Threshold**: **Low**. ⚡ **CVSS**: High severity (AV:N/PR:N). No authentication or user interaction required. Remote attackers can exploit it directly over the network.

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

🔥 **Exploits**: **Yes, Public**. 📂 Multiple PoCs exist on GitHub (e.g., NattiSamson, 0xhaggis). ⚠️ Note: Exploits may cause DoS/crashes, but shellcode execution is possible (~1 in 5-6 runs).

Q7How to self-check? (Features/Scanning)

🔍 **Check**: Scan for Serv-U FTP services. 📝 Use Nuclei templates (e.g., `CVE-2021-35211.yaml`) for automated detection. 🕵️‍♂️ Look for version strings indicating pre-15.2.3 HF2.

Q8Is it fixed officially? (Patch/Mitigation)

🛡️ **Fix**: **Yes**. 🔄 Official patch available. Upgrade to **SolarWinds Serv-U version 15.2.3 HF2** or later to resolve the memory escape vulnerability.

Q9What if no patch? (Workaround)

🚧 **No Patch?**: Isolate the server from the internet. 🚫 Block FTP ports (21, 990, etc.) via firewall. 🛑 Restrict access to trusted IPs only until patching is possible.

Q10Is it urgent? (Priority Suggestion)

🚨 **Urgency**: **CRITICAL**. 🔴 CVSS Vector indicates High impact. Active exploitation by threat actors has been reported. Patch immediately to prevent RCE.