Ubuntu USN · USN-8486-1

libssh2 vulnerabilities

Published: Tue, 30 Jun 2026 12:41

CVE-2026-55200CVE-2026-55199CVE-2025-15661

Summary

Several security issues were fixed in libssh2.

Details

It was discovered that libssh2 incorrectly handled the sftp_symlink() function. A malicious SSH server or machine-in-the-middle attacker could possibly use this issue to obtain sensitive information or cause a denial of service. (CVE-2025-15661) It was discovered that libssh2 had a pre-authentication denial of service vulnerability in the SSH_MSG_EXT_INFO handler. A malicious SSH server could possibly use this issue to cause a client CPU exhaustion loop, resulting in a denial of service. (CVE-2026-55199) It was discovered that libssh2 incorrectly handled packet length fields. A remote attacker could possibly use this issue to execute arbitrary code. This issue only affected Ubuntu 25.10 and Ubuntu 26.04 LTS. (CVE-2026-55200)

Recommended actions per Ubuntu release

StackPatch playbook auto-generated per release codename and per affected package.

Ubuntu noble

libssh2→1.11.0-4.1ubuntu0.24.04.2apt_upgrade
Standard apt upgrade. Install 1.11.0-4.1ubuntu0.24.04.2 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y libssh2
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
libssh2-1-dev→1.11.0-4.1ubuntu0.24.04.2apt_upgrade
Standard apt upgrade. Install 1.11.0-4.1ubuntu0.24.04.2 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y libssh2-1-dev
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
libssh2-1t64→1.11.0-4.1ubuntu0.24.04.2apt_upgrade
Standard apt upgrade. Install 1.11.0-4.1ubuntu0.24.04.2 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y libssh2-1t64
```
Most apt upgrades restart their service automatically. needrestart lists anything else.

Ubuntu questing

libssh2→1.11.1-1ubuntu0.25.10.2apt_upgrade
Standard apt upgrade. Install 1.11.1-1ubuntu0.25.10.2 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y libssh2
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
libssh2-1-dev→1.11.1-1ubuntu0.25.10.2apt_upgrade
Standard apt upgrade. Install 1.11.1-1ubuntu0.25.10.2 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y libssh2-1-dev
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
libssh2-1t64→1.11.1-1ubuntu0.25.10.2apt_upgrade
Standard apt upgrade. Install 1.11.1-1ubuntu0.25.10.2 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y libssh2-1t64
```
Most apt upgrades restart their service automatically. needrestart lists anything else.

Ubuntu resolute

libssh2→1.11.1-1ubuntu0.26.04.2apt_upgrade
Standard apt upgrade. Install 1.11.1-1ubuntu0.26.04.2 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y libssh2
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
libssh2-1-dev→1.11.1-1ubuntu0.26.04.2apt_upgrade
Standard apt upgrade. Install 1.11.1-1ubuntu0.26.04.2 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y libssh2-1-dev
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
libssh2-1t64→1.11.1-1ubuntu0.26.04.2apt_upgrade
Standard apt upgrade. Install 1.11.1-1ubuntu0.26.04.2 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y libssh2-1t64
```
Most apt upgrades restart their service automatically. needrestart lists anything else.

Are YOU affected by USN-8486-1?

5-second check on your actual server. Reads /etc/os-release, uname -r, and dpkg-query; matches against the live USN + Debian Security Tracker feeds; tells you whether USN-8486-1 (and any other live CVE) applies. Anonymous, no signup.

curl https://mindsparkstack.com/scan.sh | bash

Form-based quickscan Read the bash source first

Want this automated for your servers?

StackPatch runs this match against YOUR installed packages every hour

Free (3 servers) / from $9/mo (14-day free trial) / Solo $9/mo / Pro $29/mo / Team $79/mo. Indie pricing.

Start free trial →See StackPatch →Live audit log →