CVE-2026-97209
Description
A flaw was found in Elixir's Mix build tool. During partitioned dependency compilation, Mix exchanges configuration data through a predictable folder in the shared system temporary directory without properly verifying directory ownership. A local attacker on the same host can exploit this flaw by pre-creating or tampering with the configuration file to achieve arbitrary code execution with the permissions of the user running the compilation.
Statement
This vulnerability is rated as Moderate severity because exploitation requires local access on a shared multi-user system and depends on an optional, non-default feature. The attack specifically targets concurrent dependency compilation workloads that have been explicitly configured with partitioned compilation. Furthermore, exploitation hinges on a timing window where an unprivileged local user must pre-create or replace configuration files within a shared directory before worker processes consume them.
Understanding the Weakness (CWE)
Confidentiality
Technical Impact: Read Application Data
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.
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