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5.9 Medium

CVE-2025-26466 Openssh: denial-of-service in openssh

Description

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.

CVSS 3.1 detail

Vector CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Exploitable remotely over the network, without an account and without any user action; an attacker can seriously compromise confidentiality, integrity or availability.

Attack vector
Network
Attack complexity
High
Privileges required
None
Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Affected products and versions

Product Affected versions Fixed in
Red Hat Enterprise Linux 10 Versions not published
Red Hat Enterprise Linux 6 Versions not published
Red Hat Enterprise Linux 7 Versions not published
Red Hat Enterprise Linux 8 Versions not published
Red Hat Enterprise Linux 9 Versions not published
Red Hat OpenShift Container Platform 4 Versions not published
Red Hat In-Vehicle Operating System 1 Versions not published
SIMATIC S7-1500 CPU 1518-4 PN/DP MFP 3.1 3.1.0 → < 3.1.5 3.1.5
SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP 3.1 3.1.0 → < 3.1.5 3.1.5
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Product Affected versions Fixed in
SIPLUS S7-1500 CPU 1518-4 PN/DP MFP 3.1 3.1.0 → < 3.1.5 3.1.5

References

Timeline

  1. Published
  2. Last modified

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