Keycloak-services: keycloak-services: saml http-redirect binding response preserves query string leading to parameter pollution
Published Jul 31, 2026
4.7
MEDIUMCVSS 3.1
EPSS 0.33%
Description
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.
Affected products
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | |||
|---|---|---|---|---|---|---|
| Red Hat | Red Hat Build of Keycloak | affected |
|
- n/a
No data.
Red Hat Build of Keycloak
keycloak-services
Affected
Red Hat Build of Keycloak
rhbk-keycloak-rhel9/rhbk-keycloak-rhel9
Affected
Red Hat Build of Keycloak
rhbk-openshift-rhel9/rhbk-openshift-rhel9
Affected
Red Hat Data Grid 8
keycloak-services
Not affected
Red Hat JBoss Enterprise Application Platform Expansion Pack
keycloak-services
Not affected
Red Hat Single Sign-On 7
keycloak-services
Not affected
| Product | Package | State | Advisory |
|---|---|---|---|
| Red Hat Build of Keycloak | keycloak-services | Affected | n/a |
| Red Hat Build of Keycloak | rhbk-keycloak-rhel9/rhbk-keycloak-rhel9 | Affected | n/a |
| Red Hat Build of Keycloak | rhbk-openshift-rhel9/rhbk-openshift-rhel9 | Affected | n/a |
| Red Hat Data Grid 8 | keycloak-services | Not affected | n/a |
| Red Hat JBoss Enterprise Application Platform Expansion Pack | keycloak-services | Not affected | n/a |
| Red Hat Single Sign-On 7 | keycloak-services | Not affected | n/a |
No package ranges for this CVE.
Remediation
Vendor solution
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.
Red Hat statement
The Red Hat Product Security team has assessed the severity of this vulnerability as Moderate, given that exploitation requires a specific client configuration (wildcard redirect URIs) and a downstream service provider that incorrectly handles duplicate HTTP parameters. Successful exploitation allows an attacker to perform login CSRF or session swapping on the affected service provider. The vulnerability's root cause is the improper handling of the query string in the SAML HTTP-Redirect binding response, which fails to strip or validate pre-existing SAML parameters.
Red Hat mitigation
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.
Metrics
No CVSS v4.0 score for this CVE.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N
1 other source (Red Hat) ▾
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:N/I:L/A:N
No CVSS v3.0 score for this CVE.
No CVSS v2.0 score for this CVE.
This CVE is not in the KEV list.
CISA SSVC (Vulnrichment)
Stakeholder-Specific Vulnerability Categorization from CISA ADP.
Exploitation
NoneAutomatable
NoTechnical Impact
PartialDecision
n/aAssessed Jul 31, 2026 · SSVC 2.0.3
Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 1, 2026.
Score over time
Jul–Oct 2026- EPSS v5
Percentile over time
- EPSS v5
Table of values (2 key points)
Flat stretches are collapsed; showing up to 120 newest points.
| Date | Score | Percentile | Model |
|---|---|---|---|
| Oct 1, 2026 | 0.33% (0.00332) | 23.98th | v5 (v2026.06.15) |
| Jul 31, 2026 | 0.19% (0.00193) | 9.24th | v5 (v2026.06.15) |
References (4)
- https://access.redhat.com/security/cve/CVE-2026-18217 vdb-entryx_refsource_REDHATVendor Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=2508311 issue-trackingx_refsource_REDHATIssue TrackingVendor Advisory
- https://nvd.nist.gov/vuln/detail/CVE-2026-18217
- https://www.cve.org/CVERecord?id=CVE-2026-18217
| Link | Providers | Tags |
|---|---|---|
| https://access.redhat.com/security/cve/CVE-2026-18217 | vdb-entryx_refsource_REDHATVendor Advisory | |
| https://bugzilla.redhat.com/show_bug.cgi?id=2508311 | issue-trackingx_refsource_REDHATIssue TrackingVendor Advisory | |
| https://nvd.nist.gov/vuln/detail/CVE-2026-18217 | ||
| https://www.cve.org/CVERecord?id=CVE-2026-18217 |
Change history (0)
No recorded changes yet.