# CVE-2023-45666: Possible double-free or memory leak in stbi__load_gif_main in stb_image

> A double-free or memory leak in stb_image's GIF loader can cause crashes or potential code execution when processing malformed images.

- **Severity:** High 7.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 20 Oct 2023
- **Updated:** 13 Feb 2025
- **Also known as:** DEBIAN-CVE-2023-45666, UBUNTU-CVE-2023-45666

## What is CVE-2023-45666?

CVE-2023-45666 is a high-severity use after free vulnerability in nothings stb, published on 20 Oct 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

stb_image is a single file MIT licensed library for processing images.  It may look like `stbi__load_gif_main` doesn’t give guarantees about the content of output value `*delays` upon failure. Although it sets `*delays` to zero at the beginning, it doesn’t do it in case the image is not recognized as GIF and a call to `stbi__load_gif_main_outofmem` only frees possibly allocated memory in `*delays` without resetting it to zero. Thus it would be fair to say the caller of `stbi__load_gif_main` is responsible to free the allocated memory in `*delays` only if `stbi__load_gif_main` returns a non null value. However at the same time the function may return null value, but fail to free the memory in `*delays` if internally `stbi__convert_format` is called and fails. Thus the issue may lead to a memory leak if the caller chooses to free `delays` only when `stbi__load_gif_main` didn’t fail or to a double-free if the `delays` is always freed

Weakness: CWE-415 (Double Free)

## Which versions are affected by CVE-2023-45666?

It affects 1 product.


Products: Nothings Stb Image.h.

## How do I fix CVE-2023-45666?

Apply the vendor's patch.

## Is CVE-2023-45666 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-45666 exists.

## Other vulnerabilities in nothings stb

- [CVE-2019-19777](https://insights.sbomify.com/CVE-2019-19777/): Memory corruption in n/a (high 8.8)
- [CVE-2023-45664](https://insights.sbomify.com/CVE-2023-45664/): Double-free in stbi__load_gif_main_outofmem in stb_image (high 7.3)
- [CVE-2023-43281](https://insights.sbomify.com/CVE-2023-43281/): Use after free in n/a (medium 6.5)
- [CVE-2023-45661](https://insights.sbomify.com/CVE-2023-45661/): Wild address read in stbi__gif_load_next in stb_image (medium 6.5)
- [CVE-2023-45662](https://insights.sbomify.com/CVE-2023-45662/): Multi-byte read heap buffer overflow in stbi__vertical_flip in stb_image (medium 6.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-45666 and fix it if it is affected.

What it is: CVE-2023-45666 is a high-severity use after free vulnerability in nothings stb, published on 20 Oct 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-45666 exists.

Affected product: nothings stb. 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-2023-45666/ (Markdown: https://insights.sbomify.com/CVE-2023-45666/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-45666
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-45666
- OSV: https://osv.dev/vulnerability/CVE-2023-45666

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From sbomify Insights: https://insights.sbomify.com/CVE-2023-45666/
Summaries are generated and may contain mistakes; the official description above is the record.