# CVE-2026-59357: Self-UAA OIDC Configuration allows JWT injection to establish unauthorized sessions

> Authenticated users can bypass OIDC verification in self-configured Cloud Foundry UAA zones to establish unauthorized sessions with potentially elevated privileges.

- **Severity:** Medium 6.5 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:P`)
- **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:** No
- **Published:** 6 Oct 2026
- **Updated:** 6 Oct 2026
- **Also known as:** GHSA-9cjx-f7j2-23c5

## What is CVE-2026-59357?

CVE-2026-59357 is a medium-severity authentication bypass vulnerability in Cloud Foundry UAA, published on 6 Oct 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

Insufficient verification of data authenticity (CWE-345) in the external OIDC login callback in Cloud Foundry UAA v4.5.0 to v79.6.0 (inclusive) allows an authenticated UAA user to bypass the OAuth authorization-code exchange and establish an authenticated external-OIDC browser session, via submitting a UAA access token or a cross-client ID token as the callback’s id_token parameter.

The issue only manifests when a UAA zone is configured with an OIDC identity provider whose issuer exactly matches that zone’s own /oauth/token endpoint (a “self-UAA” OIDC configuration). In this configuration, the callback takes a supplied id_token directly instead of requiring the authorization code exchange, and does not verify that the token was actually issued as an ID token for the specific self-OIDC relying-party client. An attacker holding any valid UAA JWT for themselves — including a plain access token with only uaa.user scope, or a valid ID token issued to an unrelated client such as cf — can present it as the callback’s id_token and be authenticated into a mapped local (“shadow”) account. Because the resulting session is not verified against the originating token’s true audience or user_id, its effective privilege depends entirely on the shadow account’s group memberships, which can include administrative scopes such as clients.write.

Exploitation requires a valid UAA user JWT, a valid browser login state for the target zone, and the presence of a self-referential OIDC provider configuration — this is not a pre-authentication vulnerability, and does not by itself grant privileges beyond those already held by the mapped shadow account.

Weakness: CWE-345 (Insufficient Verification of Data Authenticity)

## Which versions are affected by CVE-2026-59357?


## How do I fix CVE-2026-59357?

No fix has been published for CVE-2026-59357 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-59357 being exploited?

There is no known exploitation of CVE-2026-59357 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-59357 and fix it if it is affected.

What it is: CVE-2026-59357 is a medium-severity authentication bypass vulnerability in Cloud Foundry UAA, published on 6 Oct 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-2026-59357 in the wild and no public exploit code.

Affected product: Cloud Foundry UAA. 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-2026-59357/ (Markdown: https://insights.sbomify.com/CVE-2026-59357/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-59357
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-59357
- OSV: https://osv.dev/vulnerability/CVE-2026-59357

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-59357/
Summaries are generated and may contain mistakes; the official description above is the record.