# CVE-2026-110601: libsixel before 1.8.7-r1 and 1.9.0 through 1.10.5 Heap Out-of-Bounds Write via GIF

> Attackers can trigger heap corruption or crashes in libsixel by supplying a crafted GIF with an invalid transparent color index.

- **Severity:** Medium 5.8 (`CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:P/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 14 Oct 2026
- **Updated:** 20 Oct 2026
- **Also known as:** DEBIAN-CVE-2026-110601, GHSA-5j3r-7cc6-965h, UBUNTU-CVE-2026-110601

## What is CVE-2026-110601?

CVE-2026-110601 is a medium-severity memory corruption vulnerability in saitoha libsixel, published on 14 Oct 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

libsixel before 1.8.7-r1 and 1.9.0 through 1.10.5 contains a heap out-of-bounds write vulnerability in gif_init_frame() in src/fromgif.c, which never checks the GIF transparent color index against the palette size. Attackers can supply a crafted GIF with a small color table and large transparent index, processed with a background color set, to write bytes past the palette buffer, causing heap corruption or crashes.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2026-110601?


## How do I fix CVE-2026-110601?

Upgrade to a fixed version.

## Is CVE-2026-110601 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-110601 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-110601 and fix it if it is affected.

What it is: CVE-2026-110601 is a medium-severity memory corruption vulnerability in saitoha libsixel, published on 14 Oct 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-110601 exists.

Affected product: saitoha libsixel. 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-2026-110601/ (Markdown: https://insights.sbomify.com/CVE-2026-110601/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-110601
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-110601
- OSV: https://osv.dev/vulnerability/CVE-2026-110601

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-110601/
Summaries are generated and may contain mistakes; the official description above is the record.