CVE-2026-9801Keycloak: keycloak: denial of service via malformed ldap password policy response
- 4.9MediumCVSS base score
- 0.48%Exploitation in 30 daysEPSS · top 58% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
A flaw was found in Keycloak. A remote attacker with high privileges, such as a realm administrator configuring a malicious Lightweight Directory Access Protocol (LDAP) server or an attacker compromising an upstream LDAP server, could exploit this vulnerability. By sending a malformed LDAP password policy response during a password authentication request, the attacker can trigger an OutOfMemoryError. This causes the Keycloak Java Virtual Machine (JVM) to terminate, leading to a denial of service (DoS) for all realms on the affected node.
Timeline
ID reserved
By redhat
Published
- 29 days later
· 29 days later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| redhatCNA (assigner) | 3.1 | Medium4.9 | CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H |
| NVDNVD · Modified | 3.1 | Medium4.9 | CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 0.48% · top 58% of all CVEs (12 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 4.9.
Affected products
Red Hat · Red Hat build of Keycloak 26.4
- unaffected 26.4.13-1 – < *
Red Hat · Red Hat build of Keycloak 26.4
- unaffected 26.4-19 – < *
Red Hat · Red Hat build of Keycloak 26.4
- unaffected 26.4-19 – < *
Red Hat · Red Hat build of Keycloak 26.4.13
All versions: unaffected
Red Hat · Red Hat build of Keycloak 26.6
- unaffected 26.6.3-3 – < *
Red Hat · Red Hat build of Keycloak 26.6
- unaffected 26.6-6 – < *
Red Hat · Red Hat build of Keycloak 26.6
- unaffected 26.6-6 – < *
Red Hat · Red Hat build of Keycloak 26.6.3
All versions: unaffected
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- Mavenorg.keycloak:keycloak-ldap-federationGHSA-f6r7-6w34-x2gp (opens in a new tab)
What to do
Workaround: To mitigate this vulnerability, ensure that Keycloak's LDAP user-storage providers are configured to connect only to trusted and secure LDAP servers. Avoid configuring LDAP federation with unverified or potentially malicious LDAP endpoints. Additionally, always use TLS for LDAP connections to prevent Man-in-the-Middle attacks. If an upstream LDAP server is compromised, it should be isolated and secured immediately.
References
References6
- RHSA-2026:25097 (opens in a new tab)vendor-advisoryx_refsource_REDHAT
- RHSA-2026:25098 (opens in a new tab)vendor-advisoryx_refsource_REDHAT
- RHSA-2026:30049 (opens in a new tab)vendor-advisoryx_refsource_REDHAT
- RHSA-2026:30050 (opens in a new tab)vendor-advisoryx_refsource_REDHAT
- https://access.redhat.com/security/cve/CVE-2026-9801 (opens in a new tab)vdb-entryx_refsource_REDHAT
- RHBZ#2482473 (opens in a new tab)issue-trackingx_refsource_REDHAT
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-32718 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-f6r7-6w34-x2gp (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-9801)Record last updated .