# CVE-2026-5321: vanna-ai vanna FastAPI/Flask Server cross-domain policy

> The vanna-ai library's FastAPI/Flask server uses a permissive cross-domain policy, allowing untrusted domains to bypass security restrictions.

- **Severity:** Medium 5.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/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:** No
- **Published:** 2 Apr 2026
- **Updated:** 2 Apr 2026
- **Also known as:** GHSA-fp27-q2f5-phx3

## What is CVE-2026-5321?

CVE-2026-5321 is a medium-severity vulnerability in vanna-ai vanna, published on 2 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

A flaw has been found in vanna-ai vanna up to 2.0.2. Affected by this issue is some unknown functionality of the component FastAPI/Flask Server. Executing a manipulation can lead to permissive cross-domain policy with untrusted domains. The attack can be launched remotely. The exploit has been published and may be used. The vendor was contacted early about this disclosure but did not respond in any way.

Weakness: CWE-942 (Permissive Cross-domain Security Policy with Untrusted Domains), CWE-346 (Origin Validation Error)

## Which versions are affected by CVE-2026-5321?


## How do I fix CVE-2026-5321?

No fix has been published for CVE-2026-5321 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-5321 being exploited?

There is no known exploitation of CVE-2026-5321 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-5321 and fix it if it is affected.

What it is: CVE-2026-5321 is a medium-severity vulnerability in vanna-ai vanna, published on 2 Apr 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-2026-5321 in the wild and no public exploit code.

Affected product: vanna-ai vanna. 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-2026-5321/ (Markdown: https://insights.sbomify.com/CVE-2026-5321/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-5321
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-5321
- OSV: https://osv.dev/vulnerability/CVE-2026-5321

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-5321/
Summaries are generated and may contain mistakes; the official description above is the record.