Detect CVE-2026-33646: Mise Arbitrary Code Execution via Tera Template Injection in .tool-versions in Sumo Logic CSE
Detects exploitation of CVE-2026-33646, a critical trust bypass vulnerability in mise (formerly rtx) versions prior to 2026.3.10. Attackers can embed Tera template directives inside .tool-versions files to achieve arbitrary code execution when mise processes the file, bypassing trust checks. CVSS 9.6. PoC public.
MITRE ATT&CK
- Tactic
- Execution Persistence Defense Evasion
Sumo Detection Query
_sourceCategory=endpoint/sysmon OR _sourceCategory=endpoint/linux
| where TargetFilename matches "*.tool-versions" or ProcessName matches "*mise*"
| eval has_template = if(CommandLine matches "{%*" or CommandLine matches "{{*", 1, 0)
| eval is_mise_exec = if(ProcessName matches "*mise*" and (CommandLine matches "*install*" or CommandLine matches "*trust*" or CommandLine matches "*exec*" or CommandLine matches "*run*"), 1, 0)
| eval is_tool_versions_write = if(TargetFilename matches "*.tool-versions*" and has_template=1, 1, 0)
| stats sum(is_tool_versions_write) as template_writes, sum(is_mise_exec) as mise_execs by _sourceHost, _sourceIP, _user, _timeslice 5m
| where template_writes > 0 and mise_execs > 0
| sort by _timeslice desc
| fields _timeslice, _sourceHost, _sourceIP, _user, template_writes, mise_execsSumo Logic query correlating .tool-versions file writes with Tera template markers and mise execution events within 5-minute time slices on the same host.
Data Sources
False Positives & Tuning
- CI/CD runner hosts where mise is a standard build tool
- Developer machines with mise-managed multi-language projects
- Infrastructure-as-code pipelines that programmatically generate .tool-versions files
Other platforms for CVE-2026-33646
Testing Methodology
Validate this detection against 4 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1Inject Tera system() call into .tool-versions and invoke mise install
Expected signal: File write event for .tool-versions, followed by mise process launch, followed by child process executing 'id' or shell writing to /tmp/mise-pwned.txt
- Test 2Malicious .tool-versions via Git Clone Simulation
Expected signal: Directory creation, .tool-versions file write by shell (not interactive mise), then mise process launch with install argument
- Test 3mise trust bypass via template in project-local .tool-versions
Expected signal: osascript child process spawned from mise with suspicious arguments, .tool-versions read by mise process
- Test 4Enumerate environment variables via Tera template injection
Expected signal: File write of .tool-versions, mise process launch, child write to /tmp/mise-env-leak.txt containing environment variable value
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