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CVE-2026-18217

LOW 3.4

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

A flaw was found in the SAML protocol implementation of Keycloak, an open-source identity and access management solution. The issue occurs when Keycloak handles SAML authentication requests using the HTTP-Redirect binding. If a client is configured with a wildcard redirect URL, an attacker can craft a request that includes malicious parameters. When a user authenticates, Keycloak appends its legitimate response to the attacker's parameters. This can cause some service providers to process the attacker's data instead of the real login information, potentially leading to a user being logged into the wrong account.

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 · 9th percentile

○ In CISA KEV ○ Public exploit / PoC

Impact if exploited

3.4CVSS 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: A user must take an action (click / open a file)
  • ⚠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-2026-18217/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-2026-18217/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:R/S:C/C:N/I:L/A:N

Known Affected Software Configurations

VendorProductVersion range
RedhatBuild Of Keycloak*

All CVSS metrics

  • LOW 3.4 v3.1 · CNA Primary
    CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:N/I:L/A:N
  • LOW 3.4 v3.1 · NVD Secondary
    CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:N/I:L/A:N
  • MEDIUM 4.7 v3.1 · NVD Primary
    CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N

References

Advisories

Sources: NVD · CVE.org · EPSS