CVE-2025-26466

Openssh: denial-of-service in openssh

Severity Score

5.9

*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

*Multiple Sources

Exploited in Wild

*KEV

Decision

Track*

*SSVC

Descriptions

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.

It was discovered that the OpenSSH client incorrectly handled the non-default VerifyHostKeyDNS option. If that option were enabled, an attacker could possibly impersonate a server by completely bypassing the server identity check. It was discovered that OpenSSH incorrectly handled the transport-level ping facility. A remote attacker could possibly use this issue to cause OpenSSH clients and servers to consume resources, leading to a denial of service. This issue only affected Ubuntu 24.04 LTS and Ubuntu 24.10.

*Credits: N/A

Attack Vector

Network

Attack Complexity

High

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Attack Vector

Network

Attack Complexity

High

Authentication

None

Confidentiality

None

Integrity

None

Availability

Complete

* Common Vulnerability Scoring System

SSVC

Decision:Track*

Exploitation

Poc

Automatable

Tech. Impact

Partial

* Organization's Worst-case Scenario

Timeline

2025-02-10 CVE Reserved
2025-02-18 CVE Published
2025-02-18 First Exploit
2025-03-05 CVE Updated
2025-03-05 EPSS Updated
---------- Exploited in Wild
---------- KEV Due Date

CWE

CWE-400: Uncontrolled Resource Consumption

CAPEC

References (6)

URL	Tag	Source
https://access.redhat.com/security/cve/CVE-2025-26466	Vdb Entry
https://bugzilla.redhat.com/show_bug.cgi?id=2345043	Issue Tracking
https://www.qualys.com/2025/02/18/openssh-mitm-dos.txt
https://security.netapp.com/advisory/ntap-20250228-0002

URL	Date	SRC
https://github.com/rxerium/CVE-2025-26466	2025-02-18
https://github.com/jhonnybonny/CVE-2025-26466	2025-02-19

URL	Date	SRC

URL	Date	SRC

Affected Vendors, Products, and Versions

Vendor		Product				Version		Other		Status
Vendor	Product	Version	Other	Status	<-- -->	Vendor	Product	Version	Other	Status
Red Hat Search vendor "Red Hat"		Enterprise Linux Search vendor "Red Hat" for product "Enterprise Linux"				*		-		Affected
Redhat Search vendor "Redhat"		Openshift Search vendor "Redhat" for product "Openshift"				*		-		Affected
Canonical Search vendor "Canonical"		Ubuntu Linux Search vendor "Canonical" for product "Ubuntu Linux"				*		-		Affected
Fedoraproject Search vendor "Fedoraproject"		Fedora Search vendor "Fedoraproject" for product "Fedora"				*		-		Affected
Freebsd Search vendor "Freebsd"		Freebsd Search vendor "Freebsd" for product "Freebsd"				*		-		Affected
Opensuse Search vendor "Opensuse"		Leap Search vendor "Opensuse" for product "Leap"				*		-		Affected
Redhat Search vendor "Redhat"		Enterprise Linux Search vendor "Redhat" for product "Enterprise Linux"				*		-		Affected
Redhat Search vendor "Redhat"		Openshift Search vendor "Redhat" for product "Openshift"				*		-		Affected
Slackware Search vendor "Slackware"		Slackware Linux Search vendor "Slackware" for product "Slackware Linux"				*		-		Affected
Suse Search vendor "Suse"		Sle-module-basesystem Search vendor "Suse" for product "Sle-module-basesystem"				*		-		Affected
Suse Search vendor "Suse"		Sle-module-desktop-applications Search vendor "Suse" for product "Sle-module-desktop-applications"				*		-		Affected