CVE-2026-18211Keycloak-services: keycloak-services: secure-client-uris policy bypass via localhost-prefixed domains
- 4.2MediumCVSS base score
- 0.31%Exploitation in 30 daysEPSS · top 76% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
A flaw was found in the secure-client-uris client policy executor within Keycloak core services. This component is responsible for enforcing security requirements on client configurations, such as requiring encrypted connections for redirect URIs. Due to an improper check that only looks at the start of a web address rather than properly verifying the host, an attacker can bypass these security restrictions by using a specially crafted domain name. This could allow an attacker to intercept sensitive authentication codes over unencrypted connections.
Timeline
ID reserved
By redhat
- 2 days later
· 2 days later
Published
- 31 days later
· 31 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 | Medium4.2 | CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N |
| NVDNVD · Analyzed | 3.1 | Medium5.4 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N |
- EPSS (exploitation in 30 days)
- 0.31% · top 76% 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 4.2.
Affected products
Red Hat · Red Hat Build of Keycloak
All versions: affected
Red Hat · Red Hat Build of Keycloak
All versions: affected
Red Hat · Red Hat Build of Keycloak
All versions: affected
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
References2
- https://access.redhat.com/security/cve/CVE-2026-18211 (opens in a new tab)vdb-entryx_refsource_REDHAT
- RHBZ#2508306 (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-2026-51483 (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-2026-18211)Record last updated .