CVE-2026-86836
Published on September 14, 2026
In Eclipse Ankaios versions 0.1.0 through 1.0.2, the agent creates workload files and Control Interface named pipes (FIFOs) under a predictable path derived from the agent name and a hash of the workload's runtime configuration. If a directory or FIFO already exists at that path when the agent (re)starts, the agent reuses it based only on an existence and/or file-type check, without validating its owner or permissions. A local, unprivileged user with write access to the same base directory (by default under `$TMPDIR/ankaios`, e.g. shared `/tmp`) can pre-create this path hierarchy, including the two Control Interface FIFOs, before the agent starts. The agent then treats the attacker-owned FIFOs as the legitimate Control Interface for the targeted workload. The attacker can complete the Control Interface handshake and issue requests using that workload's configured `controlInterfaceAccess` permissions, allowing impersonation of the workload and, depending on its configured permissions, unauthorized reading and/or modification of the cluster's desired state.
Vulnerability Analysis
CVE-2026-86836 is exploitable with local system access, and requires small amount of user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity and availability.
Weakness Types
Creation of Temporary File in Directory with Insecure Permissions
The software creates a temporary file in a directory whose permissions allow unintended actors to determine the file's existence or otherwise access that file. On some operating systems, the fact that the temporary file exists may be apparent to any user with sufficient privileges to access that directory. Since the file is visible, the application that is using the temporary file could be known. If one has access to list the processes on the system, the attacker has gained information about what the user is doing at that time. By correlating this with the applications the user is running, an attacker could potentially discover what a user's actions are. From this, higher levels of security could be breached.
Incorrect Default Permissions
During installation, installed file permissions are set to allow anyone to modify those files.
What is a TOCTTOU Vulnerability?
The software checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check. This can cause the software to perform invalid actions when the resource is in an unexpected state. This weakness can be security-relevant when an attacker can influence the state of the resource between check and use. This can happen with shared resources such as files, memory, or even variables in multithreaded programs.
CVE-2026-86836 has been classified to as a TOCTTOU vulnerability or weakness.
Affected Versions
Eclipse Foundation Eclipse Ankaios:- Version 0.1.0, <= 1.0.2 is affected.