# CVE-2017-1000421: Use after free in n/a

> A use-after-free vulnerability in Gifsicle's gifview allows attackers to execute arbitrary code via a crafted GIF file.

- **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:** 2 Jan 2018
- **Updated:** 5 Aug 2024
- **Also known as:** DEBIAN-CVE-2017-1000421, DLA-1233-1, DSA-4084-1, GHSA-vp7h-g9mh-c77g, MGASA-2018-0086, UBUNTU-CVE-2017-1000421

## What is CVE-2017-1000421?

CVE-2017-1000421 is a critical use after free vulnerability in Debian Debian Linux, published on 2 Jan 2018. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Gifsicle gifview 1.89 and older is vulnerable to a use-after-free in the read_gif function resulting potential code execution

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2017-1000421?

It affects 2 products.


Products: Debian Debian Linux, Lcdf Gifsicle.

## How do I fix CVE-2017-1000421?

Upgrade to a fixed version.

## Is CVE-2017-1000421 being exploited?

There is no known exploitation of CVE-2017-1000421 in the wild and no public exploit code.

## Other vulnerabilities in Debian Debian Linux

- [CVE-2015-3306](https://insights.sbomify.com/CVE-2015-3306/): ProFTPD Improper Access Control (critical 10.0, exploited in the wild)
- [CVE-2025-49113](https://insights.sbomify.com/CVE-2025-49113/): RoundCube Webmail Deserialization of Untrusted Data (critical 9.9, exploited in the wild)
- [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild)
- [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild)
- [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2017-1000421 and fix it if it is affected.

What it is: CVE-2017-1000421 is a critical use after free vulnerability in Debian Debian Linux, published on 2 Jan 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-2017-1000421 in the wild and no public exploit code.

Affected product: Debian Debian 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-2017-1000421/ (Markdown: https://insights.sbomify.com/CVE-2017-1000421/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2017-1000421
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2017-1000421
- OSV: https://osv.dev/vulnerability/CVE-2017-1000421

---
From sbomify Insights: https://insights.sbomify.com/CVE-2017-1000421/
Summaries are generated and may contain mistakes; the official description above is the record.