# CVE-2026-33869: Mastodon has a denial of service for quote authorization

> An attacker can prevent quote processing on Mastodon servers by exploiting a flaw in quote authorization logic.

- **Severity:** Medium 4.8 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 27 Mar 2026
- **Updated:** 27 Mar 2026
- **Also known as:** BIT-mastodon-2026-33869, GHSA-q4g8-82c5-9h33

## What is CVE-2026-33869?

CVE-2026-33869 is a medium-severity denial of service vulnerability in mastodon, published on 27 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Mastodon is a free, open-source social network server based on ActivityPub. In versions on the 4.5.x branch prior to 4.5.8 and on the 4.4.x branch prior to 4.4.15, an attacker that knows of a quote before it has reached a server can prevent it from being correctly processed on that server. The vulnerability has been patched in Mastodon 4.5.8 and 4.4.15. Mastodon 4.3 and earlier are not affected because they do not support quotes.

Weakness: CWE-863 (Incorrect Authorization)

## Which versions are affected by CVE-2026-33869?

1 open source package ship an affected version, including mastodon. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `mastodon` | Bitnami | From 4.4.0 | 4.4.15, 4.5.8 |

Products: Joinmastodon Mastodon.

## How do I fix CVE-2026-33869?

Upgrade mastodon to a fixed version for your release line: 4.4.15 or 4.5.8.

## Is CVE-2026-33869 being exploited?

There is no known exploitation of CVE-2026-33869 in the wild and no public exploit code.

## Other vulnerabilities in mastodon

- [CVE-2023-36460](https://insights.sbomify.com/CVE-2023-36460/): Mastodon vulnerable to arbitrary file creation through media attachments (critical 10.0)
- [CVE-2022-2166](https://insights.sbomify.com/CVE-2022-2166/): Improper Restriction of Excessive Authentication Attempts in mastodon/mastodon (critical 9.8)
- [CVE-2022-24307](https://insights.sbomify.com/CVE-2022-24307/): Missing authorization in n/a (critical 9.8)
- [CVE-2018-21018](https://insights.sbomify.com/CVE-2018-21018/): Auth bypass in n/a (critical 9.8)
- [CVE-2024-23832](https://insights.sbomify.com/CVE-2024-23832/): Mastodon Remote user impersonation and takeover (critical 9.4)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-33869 and fix it if it is affected.

What it is: CVE-2026-33869 is a medium-severity denial of service vulnerability in mastodon, published on 27 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-33869 in the wild and no public exploit code.

Affected packages and fixed versions:
- mastodon (Bitnami): affected from 4.4.0; fixed in 4.4.15, 4.5.8

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-2026-33869/ (Markdown: https://insights.sbomify.com/CVE-2026-33869/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-33869
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-33869
- OSV: https://osv.dev/vulnerability/CVE-2026-33869

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-33869/
Summaries are generated and may contain mistakes; the official description above is the record.