CVE-2026-15554: Undertow-core: undertow: authentication bypass via ajp ssl_cert/is_ssl forgery

Severity: high (CVSS 7.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-08-11 · updated 2026-10-20
Weakness: CWE-295

Description

the Undertow AJP listener honours forged ssl_cert and is_ssl AJP attributes without requiring any shared-secret authentication. This enables an unauthenticated attacker with direct TCP access to port 8009 to bypass CLIENT-CERT authentication by injecting a forged X.509 certificate via the AJP protocol.

Affected products

Red Hat JBoss Enterprise Application Platform 7.4 ELS on RHEL 7: all versions — fixed in 0:1.10.0-46.Final_redhat_00044.1.el7eap, 0:1.5.26-2.Final_redhat_00001.1.el7eap, 0:2.16.0-22.redhat_00057.1.el7eap, 0:2.18.8-1.redhat_00003.1.el7eap, 0:2.2.40-2.SP3_redhat_00001.1.el7eap, 0:2.3.14-11.SP11_redhat_00001.1.el7eap
Red Hat JBoss Enterprise Application Platform 7.4 ELS on RHEL 8: all versions — fixed in 0:1.10.0-46.Final_redhat_00044.1.el8eap, 0:1.5.26-2.Final_redhat_00001.1.el8eap, 0:2.16.0-22.redhat_00057.1.el8eap, 0:2.18.8-1.redhat_00003.1.el8eap, 0:2.2.40-1.SP3_redhat_00001.1.el8eap, 0:2.3.14-11.SP11_redhat_00001.1.el8eap
Red Hat JBoss Enterprise Application Platform 7.4 ELS on RHEL 9: all versions — fixed in 0:1.10.0-46.Final_redhat_00044.1.el9eap, 0:1.5.26-2.Final_redhat_00001.1.el9eap, 0:2.16.0-22.redhat_00057.1.el9eap, 0:2.18.8-1.redhat_00003.1.el9eap, 0:2.2.40-1.SP3_redhat_00001.1.el9eap, 0:2.3.14-11.SP11_redhat_00001.1.el9eap
Red Hat JBoss Enterprise Application Platform 8.1.8.GA: all versions — fixed in 2.3.26.SP3-redhat-00001
Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 10: all versions — fixed in 0:1.1.9-1.redhat_00001.1.el10eap, 0:1.2.7-1.redhat_00002.1.el10eap, 0:1.85.0-1.redhat_00001.1.el10eap, 0:2.0.18-1.redhat_00001.1.el10eap, 0:2.0.5-1.Final_redhat_00001.1.el10eap, 0:2.1.0-1.redhat_00001.1.el10eap
Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 8: all versions — fixed in 0:1.1.9-1.redhat_00001.1.el8eap, 0:1.2.7-1.redhat_00002.1.el8eap, 0:1.85.0-1.redhat_00001.1.el8eap, 0:2.0.18-1.redhat_00001.1.el8eap, 0:2.0.5-1.Final_redhat_00001.1.el8eap, 0:2.1.0-1.redhat_00001.1.el8eap
Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 9: all versions — fixed in 0:1.1.9-1.redhat_00001.1.el9eap, 0:1.2.7-1.redhat_00002.1.el9eap, 0:1.85.0-1.redhat_00001.1.el9eap, 0:2.0.18-1.redhat_00001.1.el9eap, 0:2.0.5-1.Final_redhat_00001.1.el9eap, 0:2.1.0-1.redhat_00001.1.el9eap

How to fix

Upgrade to a fixed version: Red Hat JBoss Enterprise Application Platform 7.4 ELS on RHEL 7 0:1.10.0-46.Final_redhat_00044.1.el7eap, 0:1.5.26-2.Final_redhat_00001.1.el7eap, 0:2.16.0-22.redhat_00057.1.el7eap, 0:2.18.8-1.redhat_00003.1.el7eap; Red Hat JBoss Enterprise Application Platform 7.4 ELS on RHEL 8 0:1.10.0-46.Final_redhat_00044.1.el8eap, 0:1.5.26-2.Final_redhat_00001.1.el8eap, 0:2.16.0-22.redhat_00057.1.el8eap, 0:2.18.8-1.redhat_00003.1.el8eap; Red Hat JBoss Enterprise Application Platform 7.4 ELS on RHEL 9 0:1.10.0-46.Final_redhat_00044.1.el9eap, 0:1.5.26-2.Final_redhat_00001.1.el9eap, 0:2.16.0-22.redhat_00057.1.el9eap, 0:2.18.8-1.redhat_00003.1.el9eap; Red Hat JBoss Enterprise Application Platform 8.1.8.GA 2.3.26.SP3-redhat-00001; Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 10 0:1.1.9-1.redhat_00001.1.el10eap, 0:1.2.7-1.redhat_00002.1.el10eap, 0:1.85.0-1.redhat_00001.1.el10eap, 0:2.0.18-1.redhat_00001.1.el10eap; Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 8 0:1.1.9-1.redhat_00001.1.el8eap, 0:1.2.7-1.redhat_00002.1.el8eap, 0:1.85.0-1.redhat_00001.1.el8eap, 0:2.0.18-1.redhat_00001.1.el8eap; Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 9 0:1.1.9-1.redhat_00001.1.el9eap, 0:1.2.7-1.redhat_00002.1.el9eap, 0:1.85.0-1.redhat_00001.1.el9eap, 0:2.0.18-1.redhat_00001.1.el9eap. Check the vendor advisory for mitigations.

References

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