CVE-2025-9817 - Wireshark Vulnerability

Summary

Wireshark, the widely-used network protocol analyzer, has a critical vulnerability (CVE-2025-9817) affecting versions 4.4.0 to 4.4.8. The flaw causes a crash in the SSH dissector, resulting in a denial of service (DoS) condition when malicious capture files are processed. The vulnerability has been assigned a CVSS v3.1 score of 7.8, classifying it as “High.” Users are advised to update to version 4.4.9 or later to mitigate this risk.

Highlights

  • ⚠️ Denial of Service Vulnerability: CVE-2025-9817 causes Wireshark to crash when processing malicious SSH capture files.
  • 🛠️ Affected Versions: The flaw impacts Wireshark versions 4.4.0 through 4.4.8.
  • 🔐 High CVSS Score: Assigned a CVSS v3.1 score of 7.8 (High) due to its impact on confidentiality, integrity, and availability.
  • 🚨 No Active Exploits: There are no known active exploits of this vulnerability in the wild.
  • ⚡ User Interaction Required: The vulnerability requires user interaction to trigger the crash, making it less likely to be exploited remotely.
  • 🔄 Mitigation: Users should upgrade to Wireshark version 4.4.9 or later to resolve the issue.
  • 🛑 Temporary Workaround: Until an upgrade can be applied, users should avoid processing untrusted capture files.

CVE-2025-9817: Wireshark Vulnerability Causes SSH Dissector Crash

Wireshark, a popular open-source tool used for network protocol analysis, has a critical vulnerability that affects versions 4.4.0 to 4.4.8. Discovered in August 2025, the flaw (CVE-2025-9817) impacts Wireshark’s SSH dissector, causing it to crash when processing maliciously crafted capture files. This results in a denial of service (DoS) condition, making Wireshark or TShark unusable until restarted.

⚠️ What Is CVE-2025-9817?

CVE-2025-9817 is a NULL Pointer Dereference vulnerability, classified as CWE-476. The flaw arises when Wireshark attempts to process an SSH packet with a malformed structure, leading to a crash. This crash prevents the program from continuing its analysis and could impact workflows that depend on Wireshark for network diagnostics.

Wireshark is widely used by security professionals, network administrators, and developers for monitoring network traffic, and a DoS attack can disrupt critical tasks like troubleshooting and protocol analysis.

💻 Affected Wireshark Versions

This vulnerability affects Wireshark versions 4.4.0 through 4.4.8. Users who are still running these versions should upgrade to version 4.4.9 or later as soon as possible to mitigate the risk.

🚨 What Are the Potential Risks?

Although the flaw doesn’t allow attackers to execute arbitrary code, the denial of service (DoS) it causes could be significant for organizations relying on Wireshark for real-time packet analysis and troubleshooting. The crash could halt ongoing network diagnostics, potentially delaying critical security investigations or system optimizations.

The vulnerability’s CVSS score of 7.8 (High) indicates that while it’s not trivial to exploit, its potential impact on confidentiality, integrity, and availability makes it a serious concern for security and network professionals.

🛠️ Mitigation: How to Protect Your Systems

The most effective way to mitigate the CVE-2025-9817 vulnerability is to upgrade Wireshark to version 4.4.9 or later, which contains the necessary fixes to prevent the SSH dissector crash.

For users who cannot update immediately, here are some temporary measures:

  • Avoid Processing Untrusted Capture Files: Until you can update to the fixed version, refrain from opening suspicious or untrusted capture files that might trigger the vulnerability.
  • Use Wireshark’s Command-Line Tool (TShark): While TShark may also be affected, if you need to perform analysis on potentially risky capture files, consider using a controlled environment or alternate tools.

🔐 Best Security Practices for Wireshark Users

To maintain the security and integrity of your Wireshark installation, here are some best practices:

  • Keep Your Software Updated: Always apply the latest security patches and updates to prevent vulnerabilities from being exploited.
  • Regularly Monitor Security Advisories: Stay informed of new vulnerabilities and updates related to Wireshark and other critical software.
  • Test in Controlled Environments: When analyzing potentially unsafe capture files, use isolated environments to limit exposure.

Conclusion: Update Wireshark to Safeguard Your Systems

CVE-2025-9817 highlights the importance of keeping software up to date to protect against potential disruptions. While this particular vulnerability does not allow remote code execution, it can cause significant service interruptions, especially for network administrators and cybersecurity professionals. Make sure to upgrade to Wireshark version 4.4.9 or later to protect your systems from this critical flaw.

Call to Action

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Source: NVD