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Ubuntu 26.04 libssh2 Critical Denial of Service USN-8309-1

ubuntu
Calendar Grey May 26, 2026
Dist Ubuntu Esm H88
libssh2 on Ubuntu could crash due to crafted network traffic; critical update available to prevent service disruption.
libssh2 could be made to crash if it received specially crafted network traffic.

Summary

libssh2 could be made to crash if it received specially crafted

network traffic.

Software Description:

- libssh2: Client-side C library implementing the SSH2 protocol

Details:

It was discovered that libssh2 incorrectly handled username and password

length values during SSH password authentication. A remote attacker could

possibly use this issue to cause a denial of service.

Topics%20covered

Topics Covered

security advisory denial of service critical Ubuntu network attack libssh2

Update Instructions

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 26.04 LTS
  libssh2-1t64                    1.11.1-1ubuntu0.26.04.1

Ubuntu 25.10
  libssh2-1t64                    1.11.1-1ubuntu0.25.10.1

Ubuntu 24.04 LTS
  libssh2-1t64                    1.11.0-4.1ubuntu0.24.04.1

In general, a standard system update will make all the necessary changes.

References

https://ubuntu.com/security/notices/USN-8309-1

CVE-2026-7598

Severity
critical
Lowest
Low
Medium
High
Critical

Ubuntu Security Notice USN-8309-1

Topics%20covered

Topics Covered

security advisory denial of service critical Ubuntu network attack libssh2

Package Information

https://launchpad.net/ubuntu/+source/libssh2/1.11.1-1ubuntu0.26.04.1
https://launchpad.net/ubuntu/+source/libssh2/1.11.1-1ubuntu0.25.10.1
https://launchpad.net/ubuntu/+source/libssh2/1.11.0-4.1ubuntu0.24.04.1

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