# CVE-2026-32245: Tinyauth's OIDC authorization codes are not bound to client on token exchange

> A malicious OIDC client can exchange another client's authorization code to obtain user tokens without consent, allowing unauthorized access to user accounts.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:L/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 12 Mar 2026
- **Updated:** 12 Mar 2026
- **Also known as:** GHSA-xg2q-62g2-cvcm, GO-2026-4689

## What is CVE-2026-32245?

CVE-2026-32245 is a medium-severity authentication bypass vulnerability in steveiliop56 tinyauth, published on 12 Mar 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

Tinyauth is an authentication and authorization server. Prior to 5.0.3, the OIDC token endpoint does not verify that the client exchanging an authorization code is the same client the code was issued to. A malicious OIDC client operator can exchange another client's authorization code using their own client credentials, obtaining tokens for users who never authorized their application. This violates RFC 6749 Section 4.1.3. This vulnerability is fixed in 5.0.3.

Weakness: CWE-863 (Incorrect Authorization)

## Which versions are affected by CVE-2026-32245?

3 open source packages ship an affected version, including github.com/steveiliop56/tinyauth. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/steveiliop56/tinyauth` | Go | All versions | None |
| `github.com/steveiliop56/tinyauth` | Go | All versions | 1.0.1-20260311144920-9eb2d33064b7 |
| `github.com/steveiliop56/tinyauth` | Go | All versions | 1.0.1-20260311144920-9eb2d33064b7 |

Products: Tinyauth Tinyauth.

## How do I fix CVE-2026-32245?

Upgrade github.com/steveiliop56/tinyauth to 1.0.1-20260311144920-9eb2d33064b7 or later.

## Is CVE-2026-32245 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-32245 exists.

## Other vulnerabilities in steveiliop56 tinyauth

- [CVE-2026-32246](https://insights.sbomify.com/CVE-2026-32246/): Tinyauth vulnerable to TOTP/2FA bypass via OIDC authorize endpoint (high 8.5)
- [CVE-2026-33544](https://insights.sbomify.com/CVE-2026-33544/): Tinyauth has OAuth account confusion via shared mutable state on singleton service instances (high 7.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-32245 and fix it if it is affected.

What it is: CVE-2026-32245 is a medium-severity authentication bypass vulnerability in steveiliop56 tinyauth, published on 12 Mar 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-32245 exists.

Affected packages and fixed versions:
- github.com/steveiliop56/tinyauth (Go): affected all versions; no fix listed
- github.com/steveiliop56/tinyauth (Go): affected all versions; fixed in 1.0.1-20260311144920-9eb2d33064b7
- github.com/steveiliop56/tinyauth (Go): affected all versions; fixed in 1.0.1-20260311144920-9eb2d33064b7

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-2026-32245/ (Markdown: https://insights.sbomify.com/CVE-2026-32245/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-32245
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-32245
- OSV: https://osv.dev/vulnerability/CVE-2026-32245

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-32245/
Summaries are generated and may contain mistakes; the official description above is the record.