# CVE-2026-6634: usememos UpdateInstanceSetting App.tsx memos_access_token improper authorization

> Remote attackers can bypass authorization in usememos to modify instance settings, potentially leading to privilege escalation or code execution.

- **Severity:** Medium 5.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 20 Apr 2026
- **Updated:** 20 Apr 2026
- **Also known as:** GHSA-gqp3-hfc3-8q54, GO-2026-5403

## What is CVE-2026-6634?

CVE-2026-6634 is a medium-severity missing authorization vulnerability in usememos memos, published on 20 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

A weakness has been identified in usememos memos up to 0.22.1. This affects the function memos_access_token of the file src/App.tsx of the component UpdateInstanceSetting. This manipulation of the argument additionalStyle/additionalScript causes improper authorization. The attack is possible to be carried out remotely. The exploit has been made available to the public and could be used for attacks. The vendor was contacted early about this disclosure but did not respond in any way.

Weakness: CWE-285 (Improper Authorization), CWE-266 (Incorrect Privilege Assignment)

## Which versions are affected by CVE-2026-6634?

3 open source packages ship an affected version, including github.com/usememos/memos.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/usememos/memos` | Go | All versions | None |
| `github.com/usememos/memos` | Go | All versions to 0.22.1 | None |
| `github.com/usememos/memos` | Go | All versions to 0.22.1 | None |

## How do I fix CVE-2026-6634?

No fix published yet.

## Is CVE-2026-6634 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-6634 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-6634 and fix it if it is affected.

What it is: CVE-2026-6634 is a medium-severity missing authorization vulnerability in usememos memos, published on 20 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-6634 exists.

Affected packages and fixed versions:
- github.com/usememos/memos (Go): affected all versions; no fix listed
- github.com/usememos/memos (Go): affected all versions up to 0.22.1; no fix listed
- github.com/usememos/memos (Go): affected all versions up to 0.22.1; no fix listed

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-2026-6634/ (Markdown: https://insights.sbomify.com/CVE-2026-6634/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-6634
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-6634
- OSV: https://osv.dev/vulnerability/CVE-2026-6634

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-6634/
Summaries are generated and may contain mistakes; the official description above is the record.