# CVE-2026-42565: @workos/authkit-session: Open Redirect via state-derived redirect target

> Attackers can redirect users to malicious sites via unvalidated OAuth state parameters in the WorkOS AuthKit session library.

- **Severity:** Medium 4.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 11 May 2026
- **Updated:** 12 May 2026
- **Also known as:** GHSA-vvvv-983w-r7pv

## What is CVE-2026-42565?

CVE-2026-42565 is a medium-severity vulnerability in workos authkit-session, published on 11 May 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

@workos/authkit-session is a toolkit for building WorkOS AuthKit framework integrations. Prior to 0.5.1, an open redirect vulnerability exists in AuthService.handleCallback due to insufficient validation of the returnPathname value derived from the OAuth state parameter. The state parameter is round-tripped through the identity provider (IdP) and can be influenced by an attacker. The handleCallback function decodes and returns returnPathname without enforcing restrictions on origin or scheme. As a result, attacker-controlled values may be returned to the application. If this value is used directly in a redirect, it may cause the user to be redirected to an external, attacker-controlled site. This vulnerability is fixed in 0.5.1.

Weakness: CWE-601 (URL Redirection to Untrusted Site)

## Which versions are affected by CVE-2026-42565?

2 open source packages ship an affected version, including @workos/authkit-session.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `@workos/authkit-session` | npm | All versions | 0.5.1 |
| `@workos/authkit-session` | npm | All versions | 0.5.1 |

## How do I fix CVE-2026-42565?

Upgrade @workos/authkit-session to 0.5.1 or later.

## Is CVE-2026-42565 being exploited?

There is no known exploitation of CVE-2026-42565 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-42565 and fix it if it is affected.

What it is: CVE-2026-42565 is a medium-severity vulnerability in workos authkit-session, published on 11 May 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-42565 in the wild and no public exploit code.

Affected packages and fixed versions:
- @workos/authkit-session (npm): affected all versions; fixed in 0.5.1
- @workos/authkit-session (npm): affected all versions; fixed in 0.5.1

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-2026-42565/ (Markdown: https://insights.sbomify.com/CVE-2026-42565/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-42565
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-42565
- OSV: https://osv.dev/vulnerability/CVE-2026-42565

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-42565/
Summaries are generated and may contain mistakes; the official description above is the record.