# CVE-2026-54692: SAIL: XBM X10 decoder writes 2 bytes per literal into a 1-byte-per-literal buffer (heap out-of-bounds write)

> Heap out-of-bounds write in SAIL image library allows attackers to execute code or crash applications via malicious XBM files.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H`)
- **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:** 17 Sep 2026
- **Updated:** 21 Sep 2026
- **Also known as:** DEBIAN-CVE-2026-54692, GHSA-gp27-qv2x-55v5, UBUNTU-CVE-2026-54692

## What is CVE-2026-54692?

CVE-2026-54692 is a high-severity memory corruption vulnerability in HappySeaFox sail, published on 17 Sep 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

SAIL is a cross-platform library for loading and saving images with support for animation, metadata, and ICC profiles. Prior to 1.0.0, sail_codec_load_frame_v8_xbm() in src/sail-codecs/xbm/xbm.c allocates the decoded pixel buffer using the X11 one-byte-per-literal layout, but an X10 static short file causes the flat decode loop to write two file-controlled bytes per literal. When ceil(width/8) produces an odd row stride, the X10 literal count includes a padding byte for every row, but the destination has no space for those bytes, so loading the XBM through sail_load_from_file, sail_load_from_memory, or sail_start_loading_* produces a forward heap overwrite that scales with image height. The X11 static char path is not affected. The overwrite can corrupt process state, cause reliable crashes, and potentially enable code execution in a susceptible consuming application. This issue is fixed in version 1.0.0.

Weakness: CWE-787 (Out-of-bounds Write), CWE-131 (Incorrect Calculation of Buffer Size)

## Which versions are affected by CVE-2026-54692?


## How do I fix CVE-2026-54692?

Upgrade to a fixed version.

## Is CVE-2026-54692 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-54692 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-54692 and fix it if it is affected.

What it is: CVE-2026-54692 is a high-severity memory corruption vulnerability in HappySeaFox sail, published on 17 Sep 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-2026-54692 exists.

Affected product: HappySeaFox sail. 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-2026-54692/ (Markdown: https://insights.sbomify.com/CVE-2026-54692/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-54692
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-54692
- OSV: https://osv.dev/vulnerability/CVE-2026-54692

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-54692/
Summaries are generated and may contain mistakes; the official description above is the record.