# CVE-2026-90679: Auth bypass in Forgejo

> Remote attackers can spoof ActivityPub identities in Forgejo when federation is enabled, bypassing signature verification to attribute actions to arbitrary actors.

- **Severity:** Medium 4.3 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A: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:** 13 Sep 2026
- **Updated:** 15 Sep 2026
- **Also known as:** GHSA-5cjj-j77f-rq2g

## What is CVE-2026-90679?

CVE-2026-90679 is a medium-severity authentication bypass vulnerability in Forgejo, published on 13 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Forgejo 13.0.0 through 16.0.4, when "[federation] ENABLED = true" is set, has a spoofing issue that affects identity integrity but does not allow account takeover or content modification. It does not verify that the HTTP Signature on an incoming ActivityPub activity was produced by the key belonging to the actor named in the activity body. The signature verification in routers/api/v1/activitypub/reqsignature.go validates the request signature, but the inbox activity handlers subsequently read the acting identity from the attacker-controlled JSON body without binding it to the verified signing key. Additionally, the signed Digest header is not recomputed against the received request body. A remote attacker who hosts a single valid ActivityPub actor and keypair can therefore submit signature-valid activities attributed to any actor identity they name.

Weakness: CWE-348 (Use of Less Trusted Source)

## Which versions are affected by CVE-2026-90679?


## How do I fix CVE-2026-90679?

No fix has been published for CVE-2026-90679 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-90679 being exploited?

There is no known exploitation of CVE-2026-90679 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90679 and fix it if it is affected.

What it is: CVE-2026-90679 is a medium-severity authentication bypass vulnerability in Forgejo, published on 13 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-2026-90679 in the wild and no public exploit code.

Affected product: Forgejo. 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-2026-90679/ (Markdown: https://insights.sbomify.com/CVE-2026-90679/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90679
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90679
- OSV: https://osv.dev/vulnerability/CVE-2026-90679

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90679/
Summaries are generated and may contain mistakes; the official description above is the record.