# CVE-2026-15943: Keycloak-services: keycloak-services: oidc idp update reuses masked client secret after token url change

> Attackers can capture OIDC client secrets by changing token URLs while reusing masked secrets, compromising identity provider security.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 17 Jul 2026
- **Updated:** 31 Aug 2026
- **Also known as:** GHSA-rpfh-mgxm-c6hc

## What is CVE-2026-15943?

CVE-2026-15943 is a medium-severity vulnerability in Redhat Build of Keycloak, published on 17 Jul 2026. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

A flaw was found in the Keycloak keycloak-services component, which handles the management of identity providers. The issue occurs when a delegated administrator updates an OIDC identity provider using a masked client secret sentinel value. Due to improper validation, Keycloak reuses the existing real secret even if security-sensitive fields like the token URL have been changed, allowing an attacker to redirect and capture the secret.

Weakness: CWE-1288 (Improper Validation of Consistency within Input)

## Which versions are affected by CVE-2026-15943?

It affects 1 product.


Products: Redhat Build of Keycloak.

## How do I fix CVE-2026-15943?

No fix has been published for CVE-2026-15943 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-15943 being exploited?

There is no known exploitation of CVE-2026-15943 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-2026-15943 and fix it if it is affected.

What it is: CVE-2026-15943 is a medium-severity vulnerability in Redhat Build of Keycloak, published on 17 Jul 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-15943 in the wild and no public exploit code.

Affected product: Redhat Build of Keycloak. 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-2026-15943/ (Markdown: https://insights.sbomify.com/CVE-2026-15943/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-15943
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-15943
- OSV: https://osv.dev/vulnerability/CVE-2026-15943

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-15943/
Summaries are generated and may contain mistakes; the official description above is the record.