# CVE-2026-104816: Misskey: Cross-site scripting in RSS feed item links

> Attackers can execute scripts via malicious RSS feed links in Misskey, requiring an upgrade to the latest version.

- **Severity:** High 8.5 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:N/SC:L/SI:L/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 13 Oct 2026
- **Updated:** 13 Oct 2026
- **Also known as:** GHSA-p73x-6qrq-34jc

## What is CVE-2026-104816?

CVE-2026-104816 is a high-severity cross-site scripting vulnerability in misskey-dev misskey, published on 13 Oct 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

Misskey is an open source, federated social media platform. From 12.0.0 until 2026.7.0, the RSS components display feed item links from configured feeds without verifying their URL schemes. Missing URL scheme verification allows an attacker who controls feed content to provide an unsafe-scheme link that causes script execution when a user clicks it in an RSS widget. This issue is fixed in version 2026.7.0.

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

## Which versions are affected by CVE-2026-104816?


## How do I fix CVE-2026-104816?

No fix has been published for CVE-2026-104816 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-104816 being exploited?

There is no known exploitation of CVE-2026-104816 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-104816 and fix it if it is affected.

What it is: CVE-2026-104816 is a high-severity cross-site scripting vulnerability in misskey-dev misskey, published on 13 Oct 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-104816 in the wild and no public exploit code.

Affected product: misskey-dev misskey. 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-2026-104816/ (Markdown: https://insights.sbomify.com/CVE-2026-104816/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-104816
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-104816
- OSV: https://osv.dev/vulnerability/CVE-2026-104816

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-104816/
Summaries are generated and may contain mistakes; the official description above is the record.