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CVE-2026-18206

LOW 3.7

Published 2026-07-31 · Last modified 2026-07-31

A flaw was found in the keycloak-services component of Keycloak, which provides identity and access management services. The issue occurs when a realm administrator uses a wildcard domain (like *.example.com) to restrict which hosts can register or update clients. Due to improper validation, the system accepts any hostname that ends with the specified domain suffix, even if it is not a legitimate subdomain. An attacker who can control the reverse DNS of their connection can bypass these host-based restrictions, potentially allowing unauthorized client modifications.

NO EXPLOITATION SIGNALS

No known exploitation, public exploit, or elevated probability at this time. Track for changes.

Exploitation likelihood

0.2%chance of exploitation in 30 days · 10th percentile

○ In CISA KEV ○ Public exploit / PoC

Impact if exploited

3.7CVSS 3.1 · LOW

  • ConfidentialityNone
  • IntegrityLow
  • AvailabilityNone

What an attacker needs

  • ✓Access: Reachable over the network — no local access needed
  • ✓Privileges: No account or privileges required
  • ✓User interaction: No user interaction needed
  • ⚠Complexity: Needs a race window or specific setup

✓ lowers the bar for an attacker · ⚠ raises it

Proof of concept & exploit code

Test against your own equipment

curl -s https://vulnpedia.com/cve/CVE-2026-18206/poc.jsonMachine-readable PoC index for this CVE (for automation).

Listed for defensive triage, patch verification, and authorized testing on systems you own. Machine-readable: /cve/CVE-2026-18206/poc.json

Affected

Vendors Red Hat Redhat

Products Red Hat Build Of Keycloak Red Hat Data Grid 8 Red Hat Jboss Enterprise Application Platform Expansion Pack Red Hat Single Sign On 7 Build Of Keycloak

Weakness (CWE)

  • CWE-20: Improper Input Validation

CVSS vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

Known Affected Software Configurations

VendorProductVersion range
RedhatBuild Of Keycloak*

All CVSS metrics

  • LOW 3.7 v3.1 · CNA Primary
    CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
  • LOW 3.7 v3.1 · NVD Secondary
    CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

References

Advisories

Sources: NVD · CVE.org · EPSS