CVE-2022-24769 in Moby
Summary
by MITRE • 03/25/2022
Moby is an open-source project created by Docker to enable and accelerate software containerization. A bug was found in Moby (Docker Engine) prior to version 20.10.14 where containers were incorrectly started with non-empty inheritable Linux process capabilities, creating an atypical Linux environment and enabling programs with inheritable file capabilities to elevate those capabilities to the permitted set during `execve(2)`. Normally, when executable programs have specified permitted file capabilities, otherwise unprivileged users and processes can execute those programs and gain the specified file capabilities up to the bounding set. Due to this bug, containers which included executable programs with inheritable file capabilities allowed otherwise unprivileged users and processes to additionally gain these inheritable file capabilities up to the container's bounding set. Containers which use Linux users and groups to perform privilege separation inside the container are most directly impacted. This bug did not affect the container security sandbox as the inheritable set never contained more capabilities than were included in the container's bounding set. This bug has been fixed in Moby (Docker Engine) 20.10.14. Running containers should be stopped, deleted, and recreated for the inheritable capabilities to be reset. This fix changes Moby (Docker Engine) behavior such that containers are started with a more typical Linux environment. As a workaround, the entry point of a container can be modified to use a utility like `capsh(1)` to drop inheritable capabilities prior to the primary process starting.
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Analysis
by VulDB Data Team • 06/08/2025
CVE-2022-24769 represents a significant privilege escalation vulnerability within the Moby containerization framework that affects Docker Engine versions prior to 20.10.14. This vulnerability stems from improper handling of Linux process capabilities during container initialization, specifically concerning the inheritable capability set that is typically managed by the Linux kernel's capability system. The flaw allows containers to be started with non-empty inheritable Linux process capabilities, which creates an atypical runtime environment that deviates from standard Linux security practices. The vulnerability operates through the interaction between Linux capabilities and file capabilities, where programs with specified permitted file capabilities normally enable unprivileged users to gain those capabilities up to the bounding set when executed. However, due to this bug, containers containing executable programs with inheritable file capabilities permitted otherwise unprivileged users and processes to additionally gain these inheritable file capabilities up to the container's bounding set, effectively bypassing normal privilege restrictions.
The technical implementation of this vulnerability involves the manipulation of Linux process capability sets during container startup, specifically affecting how the inheritable capability set is initialized. When containers are started with this bug present, the inheritable set contains capabilities that should normally be empty or properly constrained, allowing programs with inheritable file capabilities to escalate privileges beyond what would be expected in a secure container environment. This behavior directly violates the principle of least privilege and undermines the security model that containers are designed to provide. The vulnerability is particularly impactful in scenarios where containers utilize Linux users and groups for privilege separation, as these mechanisms rely on proper capability management to maintain security boundaries. The issue is classified under CWE-250 Improper Privilege Management, which specifically addresses situations where programs or processes have more privileges than necessary or where privilege escalation occurs through improper capability handling.
The operational impact of CVE-2022-24769 extends beyond simple privilege escalation to potentially enable full system compromise when containers contain applications with file capabilities. Attackers could leverage this vulnerability to execute programs within containers that have inheritable file capabilities, thereby gaining elevated privileges that would normally be restricted to privileged users. The vulnerability affects the core container security model by creating an environment where the bounding set protection mechanism is effectively bypassed, allowing capabilities to propagate beyond their intended scope. This is particularly concerning in multi-tenant environments or when containers are used to isolate applications with different privilege requirements. The security implications are further amplified because the vulnerability does not affect the container security sandbox itself, meaning that the container's isolation properties remain intact, but the capability inheritance mechanism becomes a vector for privilege escalation.
Mitigation strategies for CVE-2022-24769 include both immediate remediation and long-term architectural changes to container security practices. The primary fix involves upgrading to Moby (Docker Engine) version 20.10.14 or later, which corrects the capability initialization behavior to match standard Linux process capability management. For existing containers that are already running, administrators must stop, delete, and recreate the containers to ensure that the inheritable capabilities are properly reset, as the fix requires a fresh container initialization to take effect. Additionally, the vulnerability can be addressed through workaround measures such as modifying container entry points to utilize utilities like capsh(1) to drop inheritable capabilities prior to the primary process starting, which effectively isolates the container from the problematic capability inheritance behavior. This vulnerability aligns with ATT&CK technique T1548.001 Privilege Escalation through Setuid and Setgid, as it enables unprivileged users to gain elevated privileges through improper capability management. The fix implemented in the patched versions ensures that containers are started with a more typical Linux environment that properly enforces capability boundaries, thereby restoring the expected security model for containerized applications and preventing unauthorized privilege escalation through file capability inheritance mechanisms.