# CVE-2026-86112: BookWyrm through 0.9.1 Missing Authorization on the Favorite and Unfavorite Endpoints

> Authenticated attackers can favorite or unfavorite private statuses, triggering unauthorized ActivityPub broadcasts and enumerating private status IDs.

- **Severity:** Medium 5.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 5 Sep 2026
- **Updated:** 24 Sep 2026
- **Also known as:** GHSA-6779-9x55-mqpq

## What is CVE-2026-86112?

CVE-2026-86112 is a medium-severity missing authorization vulnerability in bookwyrm-social bookwyrm, published on 5 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

BookWyrm through 0.9.1 fails to validate user visibility permissions in the Favorite and Unfavorite views, allowing authenticated attackers to favorite or unfavorite followers-only and direct statuses they cannot access. Attackers can POST to the favorite endpoint with a status ID to create unauthorized interactions, trigger ActivityPub broadcasts, and enumerate private status IDs through response differentiation.

Weakness: CWE-639 (Authorization Bypass Through User-Controlled Key)

## Which versions are affected by CVE-2026-86112?


## How do I fix CVE-2026-86112?

No fix has been published for CVE-2026-86112 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-86112 being exploited?

There is no known exploitation of CVE-2026-86112 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-86112 and fix it if it is affected.

What it is: CVE-2026-86112 is a medium-severity missing authorization vulnerability in bookwyrm-social bookwyrm, published on 5 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-86112 in the wild and no public exploit code.

Affected product: bookwyrm-social bookwyrm. 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-2026-86112/ (Markdown: https://insights.sbomify.com/CVE-2026-86112/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-86112
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-86112
- OSV: https://osv.dev/vulnerability/CVE-2026-86112

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-86112/
Summaries are generated and may contain mistakes; the official description above is the record.