# CVE-2026-16100: Denial of service in Red Hat Data Grid 8

> An authenticated user can cause a denial of service by exhausting memory through unbounded metric cardinality when metrics are enabled.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **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:** 5 Aug 2026
- **Updated:** 31 Aug 2026
- **Also known as:** BIT-keycloak-2026-16100, GHSA-xj3w-m54w-h7p9

## What is CVE-2026-16100?

CVE-2026-16100 is a medium-severity denial of service vulnerability in Redhat Build of Keycloak, published on 5 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

A flaw was found in the user-event metrics recording of Keycloak. When metrics are enabled, the system records raw error messages from failed account operations as Prometheus metric labels. Because these error messages can include user-supplied input like nonexistent client IDs, an authenticated user can create a massive number of unique metric entries, eventually exhausting system memory and causing the service to crash or become unavailable.

Weakness: CWE-770 (Allocation of Resources Without Limits or Throttling)

## Which versions are affected by CVE-2026-16100?

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 | 26.6.5 |

Products: Redhat Build of Keycloak.

## How do I fix CVE-2026-16100?

Upgrade keycloak to 26.6.5 or later.

## Is CVE-2026-16100 being exploited?

There is no known exploitation of CVE-2026-16100 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-2026-16100 and fix it if it is affected.

What it is: CVE-2026-16100 is a medium-severity denial of service vulnerability in Redhat Build of Keycloak, published on 5 Aug 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-2026-16100 in the wild and no public exploit code.

Affected packages and fixed versions:
- keycloak (Bitnami): affected from 26.6.0; fixed in 26.6.5

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-2026-16100/ (Markdown: https://insights.sbomify.com/CVE-2026-16100/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-16100
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-16100
- OSV: https://osv.dev/vulnerability/CVE-2026-16100

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-16100/
Summaries are generated and may contain mistakes; the official description above is the record.