# CVE-2021-40145: Use after free in n/a

> A double free vulnerability in the GD Graphics Library allows attackers to cause denial of service or potentially execute arbitrary code via crafted GD2 images.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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:** 26 Aug 2021
- **Updated:** 4 Aug 2024
- **Also known as:** ALPINE-CVE-2021-40145, AZL-6432, CLSA-2022-1644931813, CLSA-2022-1646915745, CLSA-2026-1776445382, CLSA-2026-1777541021, CLSA-2026-1777969863, CLSA-2026-1777970160, DEBIAN-CVE-2021-40145, GHSA-8rm3-jg2c-hvfh, OESA-2022-1613, UBUNTU-CVE-2021-40145

## What is CVE-2021-40145?

CVE-2021-40145 is a high-severity use after free vulnerability in n/a, published on 26 Aug 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

gdImageGd2Ptr in gd_gd2.c in the GD Graphics Library (aka LibGD) through 2.3.2 has a double free. NOTE: the vendor's position is "The GD2 image format is a proprietary image format of libgd. It has to be regarded as being obsolete, and should only be used for development and testing purposes.

Weakness: CWE-415 (Double Free)

## Which versions are affected by CVE-2021-40145?

It affects 1 product.


Products: Libgd Libgd.

## How do I fix CVE-2021-40145?

Apply the vendor's patch.

## Is CVE-2021-40145 being exploited?

There is no known exploitation of CVE-2021-40145 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2016-10166](https://insights.sbomify.com/CVE-2016-10166/): Integer overflow in n/a (critical 9.8)
- [CVE-2016-6912](https://insights.sbomify.com/CVE-2016-6912/): Use after free in n/a (critical 9.8)
- [CVE-2016-8670](https://insights.sbomify.com/CVE-2016-8670/): Integer overflow in n/a (critical 9.8)
- [CVE-2016-5767](https://insights.sbomify.com/CVE-2016-5767/): Integer overflow in n/a (high 8.8)
- [CVE-2017-6363](https://insights.sbomify.com/CVE-2017-6363/): Memory corruption in n/a (high 8.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-40145 and fix it if it is affected.

What it is: CVE-2021-40145 is a high-severity use after free vulnerability in n/a, published on 26 Aug 2021. 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-2021-40145 in the wild and no public exploit code.

Affected product: n/a. 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-2021-40145/ (Markdown: https://insights.sbomify.com/CVE-2021-40145/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-40145
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-40145
- OSV: https://osv.dev/vulnerability/CVE-2021-40145

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-40145/
Summaries are generated and may contain mistakes; the official description above is the record.