CVE-2024-29068 in snapd
Summary
by MITRE • 07/25/2024
In snapd versions prior to 2.62, snapd failed to properly check the file type when extracting a snap. The snap format is a squashfs file-system image and so can contain files that are non-regular files (such as pipes or sockets etc). Various file entries within the snap squashfs image (such as icons etc) are directly read by snapd when it is extracted. An attacker who could convince a user to install a malicious snap which contained non-regular files at these paths could then cause snapd to block indefinitely trying to read from such files and cause a denial of service.
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Analysis
by VulDB Data Team • 06/18/2025
The vulnerability identified as CVE-2024-29068 represents a critical denial of service weakness in snapd versions prior to 2.62 that stems from inadequate file type validation during snap extraction processes. This flaw specifically targets the handling of squashfs filesystem images which are the fundamental containers for snap packages in the Ubuntu snap ecosystem. Snap packages leverage squashfs format to bundle applications along with their dependencies, but this filesystem type supports various file entry types beyond standard regular files including named pipes, Unix domain sockets, and device files. The vulnerability arises when snapd attempts to process these non-regular files during extraction, particularly when reading icon files and other resources directly from the squashfs image without proper type checking mechanisms. This design oversight creates a potential attack vector where malicious actors can craft specially constructed snaps containing problematic file entries that cause snapd to hang indefinitely while attempting to read from these non-regular file types.
The technical execution of this vulnerability relies on the attacker's ability to manipulate the snap package structure to include non-regular files at specific paths where snapd expects to read regular files such as icons or metadata. When snapd processes these malicious packages, it attempts to read from these special file types without proper handling for their unique characteristics, leading to indefinite blocking behavior. The squashfs filesystem's support for various file types including FIFOs, sockets, and device files creates a scenario where snapd's file reading operations can become trapped in wait states, consuming system resources and preventing legitimate snap installations from completing. This type of vulnerability falls under CWE-248, which addresses "Uncaught Exception" conditions where programs fail to properly handle special file types, and aligns with ATT&CK technique T1499.004 for Network Denial of Service attacks. The issue demonstrates poor input validation and insufficient error handling in the snapd extraction pipeline, creating a persistent blocking condition that can be triggered simply by installing a malicious package.
The operational impact of CVE-2024-29068 extends beyond simple service disruption to potentially compromise system availability and user experience in environments where snapd is actively used for package management. System administrators and end users who install malicious snaps could experience complete blocking of the snapd service, preventing any further snap installations or updates until the blocking condition is resolved. The indefinite hanging behavior creates a resource leak scenario where system processes remain stuck in read operations, potentially leading to cascading failures in automated deployment pipelines or system management tasks that depend on snapd functionality. This vulnerability particularly affects Ubuntu and other Linux distributions that rely on snapd for package management, creating a widespread impact across desktop and server environments where the snap package ecosystem is utilized. The attack requires minimal privileges and can be executed through normal package installation flows, making it a significant concern for both individual users and enterprise environments where automated package management is common.
Mitigation strategies for CVE-2024-29068 focus primarily on upgrading to snapd version 2.62 or later, which includes proper file type validation and handling mechanisms. System administrators should implement immediate patching of affected systems and monitor for any signs of malicious package installations that might exploit this vulnerability. Additional protective measures include implementing package verification processes that scan for suspicious file types within snap packages before installation, and establishing network segmentation to limit the impact of potential exploitation. Organizations should also consider implementing monitoring solutions that can detect abnormal snapd behavior patterns indicating potential blocking conditions. The vulnerability highlights the importance of robust input validation in system-level components and demonstrates the necessity of thorough testing of filesystem handling routines. Security teams should also review their package management policies to ensure that only trusted sources are used for snap installations and consider implementing automated scanning tools that can detect potentially malicious snap packages before they are processed by the system.