CVE-2026-16100
Keycloak-services: keycloak-services: unbounded metric cardinality in user event metrics via request-controlled error text
No known exploitation. EPSS puts it in the 44th percentile. A vendor fix is available.
What to do
The vendor has published a fix. Version details are below where the sources state them.
What it is
From the CVE record
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.
In plain language
No plain-language summary for this CVE yet.
Exploitation
Where each signal puts this CVE on the scale from published to confirmed exploited.
- CISA KEV
Not in the catalog. CISA has not confirmed exploitation.
- Public exploits
No public exploit or proof of concept found in the sources we track.
- EPSS
0.6% chance of exploitation activity in the next 30 days, which ranks it in the 44th percentile of scored CVEs.
Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.
Lifecycle
16 events over 26 days, from the signal feeds we watch.
- Patch availableworkaround available, record updated
- Patch availableworkaround available, record updated
- OpenVAS check added
- Workaround availablerecord updated
- Workaround availableworkaround available, published, weakness classified, att&ck mapped, record updated, record updated
Affected products
- build of keycloakOperating Systems / linux-distro
- Red Hat build of Keycloak 26.6Security Products / identity-access-mgmt
- Red Hat build of Keycloak 26.6.5Operating Systems / linux-distro
- Red Hat Data Grid 8Databases / cache-message-queue
- Red Hat JBoss Enterprise Application Platform Expansion PackOperating Systems / linux-distro
- Red Hat Single Sign-On 7Security Products / identity-access-mgmt
Technical detail
CVSS 3.1 vector
Open in the CVSS calculatorCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Scored 6.5 by NVD.
How it is reached
- Attack Vector NetworkExploitable remotely over the network without any special conditions
- Attack Complexity LowNo special conditions — the attack can be reliably reproduced
- Privileges Required LowRequires basic user-level privileges
- User Interaction NoneNo user interaction needed — fully automated exploitation
Scope
- Scope UnchangedImpact is limited to the vulnerable component itself
Impact if exploited
- Confidentiality NoneNo confidentiality impact
- Integrity NoneNo integrity impact
- Availability HighTotal denial of service — the component is completely unavailable
Weaknesses
ATT&CK techniques
Mapped from the weaknesses above (CWE to ATT&CK), not observed in attacks.
Sources
References in the record
- access.redhat.com/errata/RHSA-2026:50848
- access.redhat.com/errata/RHSA-2026:50849
- access.redhat.com/security/cve/CVE-2026-16100
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