CVE-2026-16100Keycloak-services: keycloak-services: unbounded metric cardinality in user event metrics via request-controlled error text
- 6.5MediumCVSS base score
- 0.55%Exploitation in 30 daysEPSS · top 53% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
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.
Timeline
ID reserved
By redhat
- 19 days later
· 19 days later
Published
- 26 days later
· 26 days later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| redhatCNA (assigner) | 3.1 | Medium6.5 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
| NVDNVD · Modified | 3.1 | Medium6.5 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 0.55% · top 53% of all CVEs (14 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 6.5.
Affected products
Red Hat · Red Hat build of Keycloak 26.6
- unaffected 26.6.5-1 – < *
Red Hat · Red Hat build of Keycloak 26.6
- unaffected 26.6-11 – < *
Red Hat · Red Hat build of Keycloak 26.6
- unaffected 26.6-11 – < *
Red Hat · Red Hat build of Keycloak 26.6.5
All versions: unaffected
Red Hat · Red Hat build of Keycloak 26.6.5
All versions: unaffected
Red Hat · Red Hat build of Keycloak 26.6.5
All versions: unaffected
All versions: unaffected
Red Hat · Red Hat JBoss Enterprise Application Platform Expansion Pack
All versions: unaffected
Red Hat · Red Hat Single Sign-On 7
All versions: unaffected
What to do
Workaround: 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.
References
References4
- RHSA-2026:50848 (opens in a new tab)vendor-advisoryx_refsource_REDHAT
- RHSA-2026:50849 (opens in a new tab)vendor-advisoryx_refsource_REDHAT
- https://access.redhat.com/security/cve/CVE-2026-16100 (opens in a new tab)vdb-entryx_refsource_REDHAT
- RHBZ#2501730 (opens in a new tab)issue-trackingx_refsource_REDHAT
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-53384 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-16100)Record last updated .