Ubuntu USN · USN-8447-3

Google Guest Agent vulnerabilities

Published: Mon, 22 Jun 2026 17:23

CVE-2026-39831CVE-2026-39834CVE-2026-39830CVE-2026-46595

Summary

Several security issues were fixed in Google Guest Agent.

Details

USN-8447-1 fixed vulnerabilities in Go Cryptography. This update provides the corresponding updates for Go Cryptography code embedded in Google Guest Agent. Original advisory details: It was discovered that Go Cryptography did not properly handle SSH global request responses. A remote attacker could possibly use this issue to cause a denial of service. (CVE-2026-39830) It was discovered that Go Cryptography did not properly verify user presence when using FIDO/U2F security keys. An attacker could possibly use this issue to bypass user presence verification for hardware security keys. This issue only affected Ubuntu 20.04 LTS, Ubuntu 22.04 LTS, Ubuntu 24.04 LTS, and Ubuntu 26.04 LTS. (CVE-2026-39831) It was discovered that Go Cryptography did not properly serialize SSH agent key constraint extensions. An attacker could possibly use this issue to bypass intended key usage restrictions. This issue only affected Ubuntu 20.04 LTS, Ubuntu 22.04 LTS, Ubuntu 24.04 LTS, and Ubuntu 26.04 LTS. (CVE-2026-39832) It was discovered that Go Cryptography did not properly enforce the confirm-before-use constraint in the SSH agent keyring. An attacker could possibly use this issue to use SSH keys without the required user confirmation. (CVE-2026-39833) It was discovered that Go Cryptography had an integer overflow when handling large SSH channel writes. A remote attacker could possibly use this issue to cause a denial of service. (CVE-2026-39834) It was discovered that Go Cryptography did not properly check certificate authority key revocation. An attacker could possibly use this issue to bypass certificate authority revocation checks. This issue only affected Ubuntu 18.04 LTS, Ubuntu 20.04 LTS, Ubuntu 22.04 LTS, Ubuntu 24.04 LTS, and Ubuntu 26.04 LTS. (CVE-2026-42508) It was discovered that Go Cryptography did not properly enforce the source- address critical option for all SSH server callback types. An attacker could possibly use this issue to bypass source address authorization restrictions. This issue only affected Ubuntu 26.04 LTS. (CVE-2026-46595)

Recommended actions per Ubuntu release

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

Ubuntu bionic

google-guest-agent→20241011.01-0ubuntu1~18.04.0+esm3apt_upgrade
Standard apt upgrade. Install 20241011.01-0ubuntu1~18.04.0+esm3 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y google-guest-agent
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
google-guest-agent→20241011.01-0ubuntu1~18.04.0+esm3apt_upgrade
Standard apt upgrade. Install 20241011.01-0ubuntu1~18.04.0+esm3 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y google-guest-agent
```
Most apt upgrades restart their service automatically. needrestart lists anything else.

Ubuntu focal

google-guest-agent→20250116.00-0ubuntu1~20.04.0+esm3apt_upgrade
Standard apt upgrade. Install 20250116.00-0ubuntu1~20.04.0+esm3 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y google-guest-agent
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
google-guest-agent→20250116.00-0ubuntu1~20.04.0+esm3apt_upgrade
Standard apt upgrade. Install 20250116.00-0ubuntu1~20.04.0+esm3 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y google-guest-agent
```
Most apt upgrades restart their service automatically. needrestart lists anything else.

Ubuntu jammy

google-guest-agent→20250116.00-0ubuntu1~22.04.3apt_upgrade
Standard apt upgrade. Install 20250116.00-0ubuntu1~22.04.3 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y google-guest-agent
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
google-guest-agent→20250116.00-0ubuntu1~22.04.3apt_upgrade
Standard apt upgrade. Install 20250116.00-0ubuntu1~22.04.3 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y google-guest-agent
```
Most apt upgrades restart their service automatically. needrestart lists anything else.

Ubuntu noble

google-guest-agent→20250116.00-0ubuntu1~24.04.4apt_upgrade
Standard apt upgrade. Install 20250116.00-0ubuntu1~24.04.4 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y google-guest-agent
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
google-guest-agent→20250116.00-0ubuntu1~24.04.4apt_upgrade
Standard apt upgrade. Install 20250116.00-0ubuntu1~24.04.4 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y google-guest-agent
```
Most apt upgrades restart their service automatically. needrestart lists anything else.

Ubuntu questing

google-guest-agent→20250506.01-0ubuntu1.2apt_upgrade
Standard apt upgrade. Install 20250506.01-0ubuntu1.2 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y google-guest-agent
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
google-guest-agent→20250506.01-0ubuntu1.2apt_upgrade
Standard apt upgrade. Install 20250506.01-0ubuntu1.2 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y google-guest-agent
```
Most apt upgrades restart their service automatically. needrestart lists anything else.

Ubuntu resolute

google-guest-agent→20250506.01-0ubuntu2.1apt_upgrade
Standard apt upgrade. Install 20250506.01-0ubuntu2.1 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y google-guest-agent
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
google-guest-agent→20250506.01-0ubuntu2.1apt_upgrade
Standard apt upgrade. Install 20250506.01-0ubuntu2.1 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y google-guest-agent
```
Most apt upgrades restart their service automatically. needrestart lists anything else.

Ubuntu xenial

google-guest-agent→20240716.00-0ubuntu1~16.04.0+esm3apt_upgrade
Standard apt upgrade. Install 20240716.00-0ubuntu1~16.04.0+esm3 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y google-guest-agent
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
google-guest-agent→20240716.00-0ubuntu1~16.04.0+esm3apt_upgrade
Standard apt upgrade. Install 20240716.00-0ubuntu1~16.04.0+esm3 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y google-guest-agent
```
Most apt upgrades restart their service automatically. needrestart lists anything else.

Are YOU affected by USN-8447-3?

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