Canonical has released a series of important security updates addressing vulnerabilities in fetchmail, Go Cryptography, and multiple Linux kernel variants used across Oracle Cloud and AWS environments. These updates patch flaws that could lead to crashes, privilege leaks, or system compromises.
Ubuntu has rolled out four security notices USN-7838-1, USN-7839-1, USN-7795-4, and USN-7833-3 between October 23 and 24, 2025, targeting critical components including the mail retrieval tool fetchmail, Go cryptography libraries, and Linux kernel builds for Oracle and AWS platforms.
In USN-7838-1, Canonical fixed a vulnerability in the fetchmail SMTP client that caused improper handling of specific status code messages. A malicious server could exploit the flaw to crash the service, resulting in a denial of service. Updated packages correct this behavior to prevent remote-induced crashes.
USN-7839-1 addressed an issue in the Go Cryptography library (golang-go.crypto), discovered by researchers Damien Tournoud, Patrick Dawkins, Vince Parker, and Jules Duvivier. The bug involved incorrect handling of public keys during SSH operations, which could allow attackers to bypass authorization mechanisms and gain unauthorized access to network services.
The USN-7795-4 update resolved several vulnerabilities in the Linux kernel for Oracle Cloud systems (linux-oracle-5.4). Flaws were found in critical subsystems, including Ext4, NFS server daemon, packet sockets, network traffic control, and VMware vSockets driver. These issues could be exploited by attackers to compromise system integrity.
Finally, USN-7833-3 targeted the Linux kernel for AWS systems (linux-aws-6.14). Discovered by a team including Oleksii Oleksenko and Cedric Fournet, this update mitigates a side-channel vulnerability (CVE-2024-36350, CVE-2024-36357) affecting some AMD processors, which could leak privileged information from prior stores.
Additional fixes cover a wide range of kernel components from architectures like ARM64, RISC-V, and x86 to subsystems such as USB, NVME, networking, file systems (BTRFS, Ext4, NFS, Ceph, F2FS), and the BPF framework.
Canonical advises all Ubuntu users and administrators to apply the latest updates promptly to ensure system stability and security.
