CVE-2025-9817
Description
A flaw was found in Wireshark’s SSH dissector, caused by a missing NULL check in key exchange parameter handling. This vulnerability can trigger a segmentation fault when processing malformed SSH traffic or crafted capture files, potentially causing the application to crash and resulting in a denial of service.
Statement
This issue is considered Moderate rather than an Important flaw because its impact is limited to application availability and does not allow arbitrary code execution or information disclosure. The vulnerability leads to a segmentation fault in the SSH dissector, which can crash Wireshark or TShark, but only when the user opens a malicious capture file or analyzes traffic containing malformed SSH packets. Since exploitation requires user interaction (opening the file) or the ability to inject traffic into a monitored network, and the consequence is restricted to denial of service rather than compromising confidentiality or integrity, the severity is classified as Moderate.
Mitigation
Users should avoid opening packet captures from untrusted sources and restrict analysis to known, reliable traffic. Running Wireshark with non-privileged accounts or in a sandboxed environment can also help minimize the impact of a crash.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.5 | 7.5 | 7.8 |
| Attack Vector | Local | Network | Local |
| Attack Complexity | Low | Low | Low |
| Privileges Required | None | None | None |
| User Interaction | Required | None | Required |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | None | None | High |
| Integrity Impact | None | None | High |
| Availability Impact | High | High | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Crash, Exit, or Restart
NULL pointer dereferences usually result in the failure of the process unless exception handling (on some platforms) is available and implemented. Even when exception handling is being used, it can still be very difficult to return the software to a safe state of operation.
Integrity,Confidentiality
Technical Impact: Execute Unauthorized Code or Commands; Read Memory; Modify Memory
In rare circumstances, when NULL is equivalent to the 0x0 memory address and privileged code can access it, then writing or reading memory is possible, which may lead to code execution.
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