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Fencer Intel
low 3.4

CVE-2026-18217 json

Keycloak-services: keycloak-services: saml http-redirect binding response preserves query string leading to parameter pollution

published 3mo ago modified 3d ago also EUVD-2026-51479

cvss
3.4
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 44%
public exploits
0
none known

Summary

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.

Patch / fix

  • Red Hat Red Hat build of Keycloak 26.4 26.4-29, 26.4-30, 26.4.17-2
  • Red Hat Red Hat build of Keycloak 26.6 26.6-24, 26.6.8-2

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-18217 updated cvss 3.4

keycloak-services: keycloak-services: SAML HTTP-Redirect binding response preserves query string leading to parameter pollution

  • Red Hat build of Keycloak 26.4 rhbk/keycloak-rhel9 26.4-29, rhbk/keycloak-rhel9-operator 26.4-30, rhbk/keycloak-operator-bundle 26.4.17-2
    fixed: vendor fix RHSA-2026:95760
  • Red Hat build of Keycloak 26.4.17
    fixed: vendor fix RHSA-2026:95759
  • Red Hat build of Keycloak 26.6 rhbk/keycloak-rhel9 26.6-24, rhbk/keycloak-rhel9-operator 26.6-24, rhbk/keycloak-operator-bundle 26.6.8-2
    fixed: vendor fix RHSA-2026:95762
  • Red Hat build of Keycloak 26.6.8
    fixed: vendor fix RHSA-2026:95761
  • Red Hat Data Grid 8 keycloak-services 23.0.7 Red Hat JBoss Enterprise Application Platform Expansion Pack keycloak-services 23.0.7 Red Hat Single Sign-On 7 keycloak-services 23.0.7
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
3mo ago

Exploit prediction

0.52% chance of exploitation in the next 30 days, higher than 44% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 3.4 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:N/I:L/A:N
NVD 3.1 4.7 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N

Affected products

  • Red Hat Red Hat build of Keycloak 26.4
  • Red Hat Red Hat build of Keycloak 26.4.17
  • Red Hat Red Hat build of Keycloak 26.6
  • Red Hat Red Hat build of Keycloak 26.6.8
  • Red Hat Red Hat Data Grid 8
  • Red Hat Red Hat JBoss Enterprise Application Platform Expansion Pack
  • Red Hat Red Hat Single Sign-On 7

Classification

Weakness
  • CWE-20 Improper Input Validation

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.