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The CVE-2025-9817 vulnerability exists in the SSH dissector component of Wireshark, versions 4.4.0 to 4.4.8. When Wireshark processes SSH protocol packets, the dissector fails to properly handle specific malformed packet structures. This failure can lead to a buffer overflow or a null pointer dereference, causing the application to crash. The crash results in a denial of service, as Wireshark becomes unresponsive and terminates. Attackers can exploit this by crafting malicious SSH packets and sending them over a network. If Wireshark is capturing traffic that includes these packets, the dissector will attempt to parse them, triggering the vulnerability. This can be done remotely if the attacker has the ability to send packets to a network segment where Wireshark is monitoring. The vulnerability is particularly impactful because Wireshark is often used for network analysis and troubleshooting, and a crash can disrupt ongoing monitoring activities. The issue is fixed in Wireshark version 4.4.9 and later, where the SSH dissector has been patched to handle the malformed packets correctly. The root cause may involve insufficient validation of packet length fields or improper handling of SSH message types. By ensuring that packet data is validated before processing, the patch prevents the crash and maintains application stability. This vulnerability underscores the importance of robust input validation in network protocol dissectors to prevent denial of service attacks.
Platform: Wireshark
Version: 4.4.0-4.4.8
Vulnerability: SSH dissector DoS
Severity: Medium
date: 09/03/2025
Prediction: Patched on 09/03/2025
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wireshark -v tshark -i eth0 -f "tcp port 22" tshark -r capture.pcap -Y ssh
how Exploit:
Craft malicious SSH packets. Send to monitored network. Wireshark crashes on dissection.
Protection from this CVE:
Update to Wireshark 4.4.9. Disable SSH dissector if unused. Use network segmentation.
Impact:
Denial of service. Disrupts network analysis. Potential data loss.
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Sources:
Reported By: nvd.nist.gov
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