CVE-2025-26466
Openssh: denial-of-service in openssh
- Published
- Feb 28, 2025
- Updated
- Jun 30, 2026
- Assigning CNA
- redhat
- Evidence observed
- Aug 8, 2026
Primary CVSS
nvd · CVSS 3.1
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:HModerate · next 30 days
- Percentile
- 98.6%
- Model date
- Sep 21, 2026
EPSS is a statistical estimate, not a certainty or a measure of impact. Combine it with CVSS, KEV status, exposure and your environment.
Summary
A flaw was found in the OpenSSH package. For each ping packet the SSH server receives, a pong packet is allocated in a memory buffer and stored in a queue of packages. It is only freed when the server/client key exchange has finished. A malicious client may keep sending such packages, leading to an uncontrolled increase in memory consumption on the server side. Consequently, the server may become unavailable, resulting in a denial of service attack.
Sources
5Patch Manual para a correção das CVE-2025-26465-e-CVE-2025-26466, para sistemas sem update do OpenSSH
- CVE-2025-26466-msfExploit
CVE-2025-26466 - SSH Ping DoS Ruby module for Metasploit Framework
- CVE-2025-26466Scanner
The OpenSSH client and server are vulnerable to a pre-authentication DoS attack between versions 9.5p1 to 9.9p1 (inclusive) that causes memory and CPU consumption
Responsible use
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