# CVE-2026-11800: Org.keycloak:keycloak-services: keycloak: authentication bypass via jwt algorithm confusion

> Attackers with valid client credentials can bypass JWT signature verification to impersonate federated users and escalate privileges in Keycloak.

- **Severity:** High 8.1 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/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:** Yes
- **Published:** 25 Jun 2026
- **Updated:** 15 Jul 2026
- **Also known as:** BIT-keycloak-2026-11800, GHSA-gqj5-2xp5-3qmp

## What is CVE-2026-11800?

CVE-2026-11800 is a high-severity authentication bypass vulnerability in Redhat Build of Keycloak, published on 25 Jun 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

A flaw was found in Keycloak. This JWT algorithm confusion vulnerability in the JWT Authorization Grant flow allows an attacker with valid client credentials to bypass signature verification. By forging an assertion, the attacker can create unauthorized access tokens. This enables the attacker to impersonate any federated user linked to the affected Identity Provider, leading to unauthorized access and potential privilege escalation.

Weakness: CWE-347 (Improper Verification of Cryptographic Signature)

## Which versions are affected by CVE-2026-11800?

1 open source package ship an affected version, including keycloak. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `keycloak` | Bitnami | From 26.6.0 | 26.6.4 |

Products: Redhat Build of Keycloak.

## How do I fix CVE-2026-11800?

Upgrade keycloak to 26.6.4 or later.

## Is CVE-2026-11800 being exploited?

There is no known exploitation of CVE-2026-11800 in the wild and no public exploit code.

## Other vulnerabilities in Redhat Build of Keycloak

- [CVE-2026-15572](https://insights.sbomify.com/CVE-2026-15572/): Keycloak-services: keycloak-services: dcr protocol mapper type-swap policy bypass allows privilege escalation (high 8.8)
- [CVE-2026-3047](https://insights.sbomify.com/CVE-2026-3047/): Keycloak SAML Broken has Authentication Bypass by Primary Weakness (high 8.8)
- [CVE-2026-15573](https://insights.sbomify.com/CVE-2026-15573/): Keycloak-services: keycloak-services: authorization bypass via unnormalized uri matching in pathmatcher (high 8.1)
- [CVE-2026-16102](https://insights.sbomify.com/CVE-2026-16102/): Keycloak-services: keycloak-services: default dcr policy allows role forgery via user property mappers (high 8.1)
- [CVE-2026-1609](https://insights.sbomify.com/CVE-2026-1609/): Org.keycloak/keycloak-quarkus-server: keycloak: unauthorized access via jwt authorization grant with disabled users (high 8.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-11800 and fix it if it is affected.

What it is: CVE-2026-11800 is a high-severity authentication bypass vulnerability in Redhat Build of Keycloak, published on 25 Jun 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-2026-11800 in the wild and no public exploit code.

Affected packages and fixed versions:
- keycloak (Bitnami): affected from 26.6.0; fixed in 26.6.4

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-2026-11800/ (Markdown: https://insights.sbomify.com/CVE-2026-11800/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-11800
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-11800
- OSV: https://osv.dev/vulnerability/CVE-2026-11800

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-11800/
Summaries are generated and may contain mistakes; the official description above is the record.