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                            CERT-Renater

                Note d'Information No. 2026/VULN839
_____________________________________________________________________

DATE                : 11/08/2026

HARDWARE PLATFORM(S): /

OPERATING SYSTEM(S): Systems running Mise (Rust) versions prior to
                                     2026.7.14.
 
=====================================================================
https://github.com/jdx/mise/security/advisories/GHSA-g74g-rg72-j2p3
_____________________________________________________________________


Untrusted local .mise.toml [settings] can set the shell-interpreter
args (default_inline/default_file shell_args), giving arbitrary
command execution, because those interpreter settings were left off
the global_only denylist added for CVE-2026-55448

High
jdx published GHSA-g74g-rg72-j2p3 

Package
jdx/mise (Rust)

Affected versions
<= 2026.7.13

Patched versions
2026.7.14


Description

Summary

Untrusted local .mise.toml [settings] can set the shell interpreter args
(unix/windows default_inline / default_file shell_args), yielding
arbitrary command execution, because those command-interpreter settings
were not added to the global_only denylist the CVE-2026-55448 fix relies
on. Code execution from an untrusted repository with no trust prompt for
the malicious file, on par with the patched CVE. Confirmed at HEAD
7160170.


The defect

CVE-2026-55448 and CVE-2026-35533 fixed the fact that a local project
[settings] table is harvested by the settings preloader independent of the
trust store (an untrusted .mise.toml sets settings without the user ever
trusting it). The remediation is a per-field global_only denylist:
settings marked global_only are stripped from non-global config. The
maintainers marked the command-execution fields they knew about (the three
forge credential_command values) but did not mark the four
shell-interpreter-args settings, which are also command-execution settings
because they choose the interpreter for every command mise spawns.

The global_only denylist and the gap. In settings.toml, the three
credential_command sinks are global_only (forgejo.credential_command around
line 775, github.credential_command around 828, gitlab.credential_command
around 990). The four shell-args settings do not carry global_only:

    unix_default_file_shell_args (settings.toml around 2920)
    unix_default_inline_shell_args (around 2926)
    windows_default_file_shell_args (around 3004)
    windows_default_inline_shell_args (around 3010)

The strip logic only removes global_only keys. src/config/settings.rs
strip_local_only_settings (line 409) filters by meta.global_only
(line 416: filter_map(|(key, meta)| meta.global_only.then_some(*key))),
so any field not marked global_only survives from a local untrusted
config. The settings preload loads every config path including the
local project file (all_settings_files, line 778), and in default
(non-safe) mode there is no trust check (safe_mode defaults false, line 1141).

The sink. src/config/settings.rs default_inline_shell (line 1032) reads
self.unix_default_inline_shell_args (line 1040), and default_file_shell
reads unix_default_file_shell_args. Settings::get returns the merged
global-plus-local value minus global_only, so the untrusted project
value overrides the built-in default (sh -c -o errexit).

Injection semantics. The real command is appended after the attacker's
args, so PAYLOAD runs and the real command is demoted to $0:

    tera inline exec builtin: src/tera.rs (tera1_exec around 1358, and
around 1470) builds shell[1..] + [command] with program = shell[0]. An
attacker unix_default_inline_shell_args = "sh -c 'PAYLOAD'" yields sh -c 'PAYLOAD' .
    postinstall runner: src/backend/mod.rs around 2405 calls
cmd_body_args(shell_args, body); src/cmd.rs cmd_body_args (non-Windows,
around 520) returns program flags... body, the same demotion.
    task execution: src/task/task_executor.rs (around 916, 939, 993) uses task.shell()?.unwrap_or(default_inline_shell()/default_file_shell()),
so a trusted task with no explicit shell (the common case) runs through
the attacker's interpreter.
    hooks: src/hooks.rs (around 540, 603) also fall back to default_inline_shell().

Attacker model and reachability

An untrusted repository the developer clones and cd's into. The attacker's
.mise.toml sits in the working directory or any ancestor and is never
trusted by the victim; its [settings] table is harvested by the preloader
independent of the trust store, exactly as the two prior CVEs established.
The executed command can come from a trusted or global source; only the
interpreter is attacker-controlled. Any of these, run while the untrusted
.mise.toml is in an ancestor directory, fires it: mise run for a task
defined in the global config or a trusted parent repo (inline run, no
explicit shell); mise install of any tool with a postinstall directive;
any tera template that calls exec(...) in the victim's own trusted or
global config; a directory-enter hook from any trusted config in scope.

Proof of concept. In an untrusted repo, .mise.toml:

[settings]
unix_default_inline_shell_args = "sh -c 'id > /tmp/mise_pwned'"

The victim cd's in (does not trust the file) and later runs any global
or trusted-parent task with no explicit shell, or mise install of a
tool with a postinstall, or a config that renders
{{ exec(...) }}. mise builds sh -c 'id > /tmp/mise_pwned' <realcommand>,
so the payload runs.


Verification

Source-verified at HEAD: the four shell-args settings lack global_only
while the credential_command sinks have it, strip_local_only_settings
removes only global_only keys, default_inline_shell reads the setting,
and the exec/postinstall/task paths append the real command after the
attacker args. The load path is the same one two shipped CVEs already
proved reachable. I did not run mise end to end.


Suggested fix

Mark all four default_shell_args settings global_only = true (the same
treatment as credential_command), or flip the default-mode policy to
an allowlist so any setting not explicitly known-safe is stripped from
non-global config.

Secondary note (weaker, not the main finding): the CVE-2026-54557
path-sanitization fix added sanitize_install_version_name only inside
the HTTP backend (src/backend/http.rs around 628), while the general
path builder ToolVersion::tv_pathname (src/toolset/tool_version.rs
around 292) still only replaces ':' and '/' and does not neutralize
'..' or backslash. Impact is narrow (one level up, stays in the mise
data dir on Unix), so this is a hardening note, not a primary finding.


Tooling

I used AI assistance while investigating, but I read
strip_local_only_settings (confirming it strips only global_only), the
settings.toml entries (confirming the four shell-args settings lack
global_only while credential_command has it), default_inline_shell
(confirming it reads the setting), and the exec/postinstall/task
invocation sites (confirming the real command is appended after the
attacker args) myself at HEAD, so the incomplete fix is
source-verified.


Severity
High
7.8/ 10

CVSS v3 base metrics
Attack vector
Local
Attack complexity
Low
Privileges required
None
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

CVE ID
No known CVE

Weaknesses
Weakness CWE-78
Weakness CWE-284

Credits

    @arpitjain099 arpitjain099 Reporter


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