# CVE-2018-13259: Other in zsh before 5.6

> Truncation of long shebang lines in zsh may cause execution of unintended programs, potentially leading to arbitrary code execution.

- **Severity:** Critical 9.8 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 5 Sep 2018
- **Updated:** 5 Aug 2024
- **Also known as:** DEBIAN-CVE-2018-13259, GHSA-8vj4-q4ww-8jf3, RHSA-2019:2017, UBUNTU-CVE-2018-13259

## What is CVE-2018-13259?

CVE-2018-13259 is a critical vulnerability in Canonical Ubuntu Linux, published on 5 Sep 2018. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An issue was discovered in zsh before 5.6. Shebang lines exceeding 64 characters were truncated, potentially leading to an execve call to a program name that is a substring of the intended one.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2018-13259?

It affects 2 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `zsh` | Red Hat:enterprise_linux:7::client | All versions | 0:5.0.2-33.el7 |
| `zsh-debuginfo` | Red Hat:enterprise_linux:7::client | All versions | 0:5.0.2-33.el7 |
| `zsh-html` | Red Hat:enterprise_linux:7::client | All versions | 0:5.0.2-33.el7 |
| `zsh` | Red Hat:enterprise_linux:7::computenode | All versions | 0:5.0.2-33.el7 |
| `zsh-debuginfo` | Red Hat:enterprise_linux:7::computenode | All versions | 0:5.0.2-33.el7 |
| `zsh-html` | Red Hat:enterprise_linux:7::computenode | All versions | 0:5.0.2-33.el7 |
| `zsh` | Red Hat:enterprise_linux:7::server | All versions | 0:5.0.2-33.el7 |
| `zsh-debuginfo` | Red Hat:enterprise_linux:7::server | All versions | 0:5.0.2-33.el7 |
| `zsh-html` | Red Hat:enterprise_linux:7::server | All versions | 0:5.0.2-33.el7 |
| `zsh` | Red Hat:enterprise_linux:7::workstation | All versions | 0:5.0.2-33.el7 |
| `zsh-debuginfo` | Red Hat:enterprise_linux:7::workstation | All versions | 0:5.0.2-33.el7 |
| `zsh-html` | Red Hat:enterprise_linux:7::workstation | All versions | 0:5.0.2-33.el7 |

Products: Canonical Ubuntu Linux, Zsh Zsh.

## How do I fix CVE-2018-13259?

Upgrade to a fixed version.

## Is CVE-2018-13259 being exploited?

There is no known exploitation of CVE-2018-13259 in the wild and no public exploit code.

## Other vulnerabilities in Canonical Ubuntu Linux

- [CVE-2020-11651](https://insights.sbomify.com/CVE-2020-11651/): SaltStack Salt Authentication Bypass (critical 9.8, exploited in the wild)
- [CVE-2020-7247](https://insights.sbomify.com/CVE-2020-7247/): OpenSMTPD Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2019-16928](https://insights.sbomify.com/CVE-2019-16928/): Exim Out-of-bounds Write (critical 9.8, exploited in the wild)
- [CVE-2018-6789](https://insights.sbomify.com/CVE-2018-6789/): Exim Buffer Overflow (critical 9.8, exploited in the wild)
- [CVE-2015-2590](https://insights.sbomify.com/CVE-2015-2590/): Oracle Java SE and Java SE Embedded Remote Code Execution (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2018-13259 and fix it if it is affected.

What it is: CVE-2018-13259 is a critical vulnerability in Canonical Ubuntu Linux, published on 5 Sep 2018. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2018-13259 in the wild and no public exploit code.

Affected product: Canonical Ubuntu Linux. 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-2018-13259/ (Markdown: https://insights.sbomify.com/CVE-2018-13259/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-13259
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-13259
- OSV: https://osv.dev/vulnerability/CVE-2018-13259

---
From sbomify Insights: https://insights.sbomify.com/CVE-2018-13259/
Summaries are generated and may contain mistakes; the official description above is the record.