CVE-2026-55441: mise Task Command Injection Vulnerability (CVSS 8.6)

Technical summary

CVE-2026-55441 is a command injection vulnerability in mise's task-loading mechanism. The trust_check function, which normally gates access to config files (mise.toml, .tool-versions), is bypassed entirely for task-include directories. When mise encounters a task-include directory without a corresponding config file, it loads the default task includes and renders each task's Tera templating fields. The Tera environment in this code path has the exec() function registered, allowing {{ exec(command='...') }} directives in task YAML/TOML to execute shell commands during task enumeration. This occurs even during read-only operations such as mise tasks, mise task ls, mise run, and shell completion queries. The root cause is a logic gap: task loading on the fallback path never invokes the trust check, so no trust prompt is presented to the user, and execution happens at parse time rather than task invocation time.

Business impact

Any developer using mise who clones or pulls a malicious repository faces immediate code execution with their user privileges the moment they list tasks or trigger tab completion. This is particularly dangerous in development environments where developers routinely explore unfamiliar codebases. A compromised repository could exfiltrate credentials, steal source code, modify build outputs, or establish persistence without the developer's knowledge. The low interaction barrier (merely listing tasks is enough) and the common developer workflow of exploring a new repo make this a high-impact supply-chain vector. Teams relying on mise for onboarding or CI/CD environments are especially vulnerable.

Affected systems

mise versions prior to 2026.6.4 are affected. The vulnerability applies to any system running a vulnerable version of mise that encounters a task-include directory. Risk is highest in development environments, shared CI/CD runners, and team onboarding scenarios where developers regularly clone and explore repositories. Users on versions 2026.6.4 and later are not affected.

Exploitability

Exploitability is very high. The attack requires no special privileges, no complex interaction (listing tasks is routine), and no user interaction beyond entering a directory and running a common command. The payload is embedded in repository files that are naturally checked out when cloning. The attacker does not need to trick the user into running the task itself—execution happens during task enumeration. Shell completion, which many developers have enabled, triggers the vulnerability automatically. The CVSS 3.1 score of 8.6 (HIGH) reflects this low-friction attack surface with high impact.

Remediation

Upgrade mise to version 2026.6.4 or later immediately. The fix restores the trust check to the task-loading path, ensuring that task-include directories are gated by the same trust mechanism as config files. After upgrading, developers should review any repositories they recently cloned from untrusted sources and ensure no credentials or sensitive data were exposed. Teams should communicate the fix to all developers and CI/CD operators using mise.

Patch guidance

Apply mise version 2026.6.4 or any subsequent release. Verification: confirm the installed version with `mise --version`. Update via your system's package manager (e.g., `brew upgrade mise` on macOS, `cargo install mise@latest` for Rust installations, or your distribution's package manager). Once updated, verify the fix is in place by testing against a repository with a malicious task-include directory—the trust prompt should now appear before any task enumeration occurs. No breaking changes are expected; the update restores intended security behavior.

Detection guidance

Identify vulnerable installations by checking mise version (any version before 2026.6.4). Monitor for unexpected process execution spawned from mise task commands or shell completion handlers. Examine repositories on disk for task-include directories (mise-tasks/, .mise/tasks/, etc.) paired with suspicious Tera template syntax ({{ exec(...) }}) in task definitions. Review shell command history and process logs for command execution events coinciding with `mise tasks`, `mise task ls`, or shell completion events. In CI/CD logs, look for unexplained process execution during build initialization phases where tasks are typically enumerated.

Why prioritize this

This vulnerability should be prioritized as urgent. It combines a high CVSS score (8.6), zero-interaction exploitation (task listing is routine), and a common developer workflow (exploring new repositories). The trust bypass—a core security feature of mise—directly undermines developer confidence. Organizations with developers using mise, particularly those in open-source contribution or multi-team environments, face immediate risk. Remediation is straightforward (a single version upgrade) and carries no known operational burden, making delay unjustifiable.

Risk score, explained

The CVSS 3.1 score of 8.6 reflects: (1) low attack complexity (straightforward Tera payload injection), (2) no required privileges, (3) user interaction limited to routine task enumeration, (4) local attack vector with significant scope change (commands run with the user's full privileges across the system), and (5) high impact across confidentiality, integrity, and availability. The score correctly captures the severity despite the initial impression that task operations are read-only—execution happens at parse time, not invocation time.

Frequently asked questions