Keycloak-services: keycloak-services: unbounded metric cardinality in user event metrics via request-controlled error text
Summary
| CVE | CVE-2026-16100 |
|---|---|
| State | PUBLISHED |
| Assigner | redhat |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-08-05 15:16:37 UTC |
| Updated | 2026-08-05 19:17:24 UTC |
| 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. |
Risk And Classification
Primary CVSS: v3.1 6.5 MEDIUM from [email protected]
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Problem Types: CWE-770 | CWE-770 CWE-770 Allocation of Resources Without Limits or Throttling
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | [email protected] | Secondary | 6.5 | MEDIUM | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
| 3.1 | CNA | CVSS | 6.5 | MEDIUM | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
CVSS v3.1 Breakdown
Attack Vector
NetworkAttack Complexity
LowPrivileges Required
LowUser Interaction
NoneScope
UnchangedConfidentiality
NoneIntegrity
NoneAvailability
HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Red Hat | Red Hat Build Of Keycloak 26.6 | unaffected 26.6.5-1 * rpm | Not specified |
| CNA | Red Hat | Red Hat Build Of Keycloak 26.6 | unaffected 26.6-11 * rpm | Not specified |
| CNA | Red Hat | Red Hat Build Of Keycloak 26.6 | unaffected 26.6-11 * rpm | Not specified |
| CNA | Red Hat | Red Hat Build Of Keycloak 26.6.5 | Not specified | Not specified |
| CNA | Red Hat | Red Hat Build Of Keycloak 26.6.5 | Not specified | Not specified |
| CNA | Red Hat | Red Hat Build Of Keycloak 26.6.5 | Not specified | Not specified |
| CNA | Red Hat | Red Hat Data Grid 8 | Not specified | Not specified |
| CNA | Red Hat | Red Hat JBoss Enterprise Application Platform Expansion Pack | Not specified | Not specified |
| CNA | Red Hat | Red Hat Single Sign-On 7 | Not specified | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| bugzilla.redhat.com/show_bug.cgi | [email protected] | bugzilla.redhat.com | |
| access.redhat.com/security/cve/CVE-2026-16100 | [email protected] | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:50848 | [email protected] | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:50849 | [email protected] | access.redhat.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Red Hat would like to thank Paul Bottinelli (Trail of Bits) for reporting this issue. (en)
Additional Advisory Data
| Source | Time | Event |
|---|---|---|
| CNA | 2026-07-14T17:46:38.000Z | Reported to Red Hat. |
| CNA | 2026-08-05T02:02:00.000Z | Made public. |
Workarounds
CNA: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
There are currently no legacy QID mappings associated with this CVE.