# CVE-2026-116463: FastStone Image Viewer Box-Average Downsampler FUN_0062d96c out-of-bounds


- **Severity:** Medium 5.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:X`)
- **Exploited in the wild:** Not known
- **Fix available:** No
- **Published:** 26 Oct 2026
- **Updated:** 26 Oct 2026
- **Also known as:** GHSA-8w68-9h8m-jw4f

## What is CVE-2026-116463?

CVE-2026-116463 is a medium-severity vulnerability in FastStone Image Viewer, published on 26 Oct 2026. 

### Official description

A vulnerability was identified in FastStone Image Viewer up to 8.5. Affected is the function FUN_0062d96c of the component Box-Average Downsampler Engine. The manipulation leads to out-of-bounds read. It is possible to initiate the attack remotely. The vendor was contacted early about this disclosure but did not respond in any way.

Weakness: CWE-125 (Out-of-bounds Read), CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

## Which versions are affected by CVE-2026-116463?


## How do I fix CVE-2026-116463?

No fix has been published for CVE-2026-116463 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-116463 being exploited?

There is no known exploitation of CVE-2026-116463 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-116463 and fix it if it is affected.

What it is: CVE-2026-116463 is a medium-severity vulnerability in FastStone Image Viewer, published on 26 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-116463 in the wild and no public exploit code.

Affected product: FastStone Image Viewer. 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-2026-116463/ (Markdown: https://insights.sbomify.com/CVE-2026-116463/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-116463
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-116463
- OSV: https://osv.dev/vulnerability/CVE-2026-116463

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-116463/
Summaries are generated and may contain mistakes; the official description above is the record.