CVE-2025-26466
A flaw was found in the OpenSSH package.
Published Feb 28, 2025 · updated Oct 15, 2026 · openbsd openssh
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.
Timeline
Detection, updates, and resolution for this record.
Feb 28, 2025 · NIST NVD
Detected
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
Oct 15, 2026 · NIST NVD
Updated
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
Affected
- cpe canonical/ubuntu linux24.04
- cpe debian/debian linux11.0
- cpe openbsd/openssh9.5
- cpe openbsd/openssh9.6
- cpe openbsd/openssh9.7
- cpe openbsd/openssh9.8
- cpe openbsd/openssh9.9
Sources
- CVE.orgCVE-2025-26466
Official CVE identifier
cve.org - NIST NVDCVE-2025-26466
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 pack
nvd.nist.gov