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

> Attackers can execute arbitrary commands via shell metacharacters in log input when using the execute-on-match feature in MultiTail.

- **Severity:** High 7.3 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 13 Oct 2026
- **Updated:** 13 Oct 2026
- **Also known as:** GHSA-54vm-wwx8-856h

## What is CVE-2026-55601?

CVE-2026-55601 is a high-severity command injection vulnerability in folkertvanheusden multitail, published on 13 Oct 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official 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.

Weakness: CWE-78 (Improper Neutralization of Special Elements used in an OS Command)

## Which versions are affected by CVE-2026-55601?


## How do I fix CVE-2026-55601?

No fix has been published for CVE-2026-55601 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-55601 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-55601 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-55601 and fix it if it is affected.

What it is: CVE-2026-55601 is a high-severity command injection vulnerability in folkertvanheusden multitail, published on 13 Oct 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-55601 exists.

Affected product: folkertvanheusden multitail. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-55601/ (Markdown: https://insights.sbomify.com/CVE-2026-55601/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-55601
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-55601
- OSV: https://osv.dev/vulnerability/CVE-2026-55601

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-55601/
Summaries are generated and may contain mistakes; the official description above is the record.