CVE-2026-3872 — keycloak
CVE-2026-3872 is a Open Redirect vulnerability in keycloak. A fix is available for keycloak — see the affected versions and patch details below.
Keycloak: keycloak: information disclosure due to redirect_uri validation bypass
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-3872.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
Real-World Exposure
keycloakReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Bitnami packages — download data is not available via public APIs for these ecosystems.
Description
A flaw was found in Keycloak. This issue allows an attacker, who controls another path on the same web server, to bypass the allowed path in redirect Uniform Resource Identifiers (URIs) that use a wildcard. A successful attack may lead to the theft of an access token, resulting in information disclosure.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦Bitnami | keycloak | ≥ 26.2.0&&< 26.2.1 | 26.2.1 |
Affected Products
build of keycloakredhatDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for keycloak, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update keycloak to 26.2.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-3872 is resolved across your whole dependency graph.
Workarounds
Stop reflecting attacker-controlled destinations: resolve every redirect target against an allowlist of paths or hosts you own, prefer a server-side key over a full URL in the request, and reject absolute URLs entirely where the flow only ever needs a relative one.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
This is an Important information disclosure flaw in Keycloak's `redirect_uri` validation logic. An attacker controlling another path on the same web server could bypass allowed paths in wildcard `redirect_uri` configurations, potentially leading to access token theft. This affects Red Hat Build of Keycloak (RHBK)…
To mitigate this vulnerability, avoid using wildcards in `redirect_uri` configurations within Keycloak. Restricting `redirect_uri` to explicit, fully qualified URIs prevents the bypass of validation logic. This configuration change may require a service restart or reload to take effect.Source: Red Hat security advisory for CVE-2026-3872 (CC BY 4.0)
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat build of Keycloak 26.2 | rhbk/keycloak-operator-bundle:26.2.15-1 | RHSA-2026:6476 |
| Red Hat build of Keycloak 26.2.15 | rhbk/keycloak-rhel9 | RHSA-2026:6475 |
| Red Hat build of Keycloak 26.4 | rhbk/keycloak-operator-bundle:26.4.11-1 | RHSA-2026:6478 |
| Red Hat build of Keycloak 26.4.11 | rhbk/keycloak-rhel9 | RHSA-2026:6477 |
Frequently Asked Questions
Is CVE-2026-3872 in your dependencies?
Find it across Bitnami, including transitive dependencies.