# CVE-2026-110103: bbs-go through 4.4.6 Stored XSS via Image Upload Content-Type

> Authenticated users can upload malicious HTML or SVG files via Content-Type spoofing, leading to stored XSS and potential administrator account takeover.

- **Severity:** Medium 5.1 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 13 Oct 2026
- **Updated:** 14 Oct 2026
- **Also known as:** GHSA-rm26-pxjp-76q3

## What is CVE-2026-110103?

CVE-2026-110103 is a medium-severity cross-site scripting vulnerability in mlogclub bbs-go, published on 13 Oct 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

bbs-go through 4.4.6 contains a stored cross-site scripting vulnerability that allows authenticated users to upload HTML or SVG files by spoofing the multipart Content-Type in POST /api/upload. Attackers can upload script-bearing documents served inline from /res and send their URLs to administrators, executing script on the forum's origin.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-110103?


## How do I fix CVE-2026-110103?

No fix has been published for CVE-2026-110103 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-110103 being exploited?

There is no known exploitation of CVE-2026-110103 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-110103 and fix it if it is affected.

What it is: CVE-2026-110103 is a medium-severity cross-site scripting vulnerability in mlogclub bbs-go, published on 13 Oct 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-110103 in the wild and no public exploit code.

Affected product: mlogclub bbs-go. 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-2026-110103/ (Markdown: https://insights.sbomify.com/CVE-2026-110103/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-110103
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-110103
- OSV: https://osv.dev/vulnerability/CVE-2026-110103

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-110103/
Summaries are generated and may contain mistakes; the official description above is the record.