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Full vulnerability report · 2026
CVE-2026-15554High confidence

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

Red Hat · Red Hat JBoss Enterprise Application Platform 7.4.25

7.4HighCVSS 3.1
Recommended action
Within 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available
Distribution package intelligence

Ubuntu vendor package status

Canonical’s release and source-package findings are shown separately from local repository availability.

1 package state
Repository candidate not checked

A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.

Ubuntu releaseSource packageVendor stateFixed versionEvidence
Ubuntu 24.04 LTSnoble · esm-appsundertowUnder evaluationCanonical reports that the package might be affected and still needs evaluation or fixing.Not published in this feedCanonical record ↗Source updated 4 Sept 2026
Direct vendor intelligence

Authoritative vendor CSAF and VEX advisories

Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.

1 current
CVE-2026-15554 · CSAF 2.0 · revision 3 · finalRed Hat Product Securityundertow-core: Undertow: Authentication Bypass via AJP ssl_cert/is_ssl Forgery
2 known affected

The vendor explicitly identifies these products as affected by this CVE.

  • undertow-core as a component of Red Hat JBoss Enterprise Application Platform 7
  • undertow-core as a component of Red Hat JBoss Enterprise Application Platform 8
Summary
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.
Remediation
Before applying the update, make sure all previously released errata relevant to your system have been applied. Also, back up your existing installation, including all applications, configuration files, databases and database settings. For details on how to apply this update, refer to: https://access.redhat.com/articles/11258
Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Select the national-authority views to include. The exact source language is shown on each matched advisory. Your choice is remembered on this device and encoded in the shareable URL.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2026-55981

No EUVD known-exploited evidence

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.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
7.4 · CVSS 3.1
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available
01

What, why and how

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.

What

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.

Why

The product does not validate, or incorrectly validates, a certificate.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

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.

Why

The product does not validate, or incorrectly validates, a certificate.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path
a network path → Improper Certificate Validation → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
High: exploitation depends on specific conditions
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-295 ↗

CWE-295: Improper Certificate Validation. The product does not validate, or incorrectly validates, a certificate.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACHighAttack complexity: Successful exploitation depends on specific conditions outside the attacker's direct control.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CHighConfidentiality impact: A successful attack can cause a major loss.IHighIntegrity impact: A successful attack can cause a major loss.ANoneAvailability impact: No direct loss is represented by this metric.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
NetworkUnauthenticatedCWE-295
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

ENISA EUVD · EUVD-2026-55981Official EUVD mapping

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.

Official EUVD record
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Patch available
Affected
undertow-core as a component of Red Hat JBoss Enterprise Application Platform 7; undertow-core as a component of Red Hat JBoss Enterprise Application Platform 8
Fixed
eap7-activemq-artemis-0:2.16.0-22.redhat_00057.1.el7eap.noarch as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 7 Server; eap7-activemq-artemis-0:2.16.0-22.redhat_00057.1.el7eap.src as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 7 Server; eap7-activemq-artemis-cli-0:2.16.0-22.redhat_00057.1.el7eap.noarch as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 7 Server; eap7-activemq-artemis-commons-0:2.16.0-22.redhat_00057.1.el7eap.noarch as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 7 Server; eap7-activemq-artemis-core-client-0:2.16.0-22.redhat_00057.1.el7eap.noarch as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 7 Server; eap7-activemq-artemis-dto-0:2.16.0-22.redhat_00057.1.el7eap.noarch as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 7 Server; eap7-activemq-artemis-hornetq-protocol-0:2.16.0-22.redhat_00057.1.el7eap.noarch as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 7 Server; eap7-activemq-artemis-hqclient-protocol-0:2.16.0-22.redhat_00057.1.el7eap.noarch as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 7 Server; eap7-activemq-artemis-jdbc-store-0:2.16.0-22.redhat_00057.1.el7eap.noarch as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 7 Server; eap7-activemq-artemis-jms-client-0:2.16.0-22.redhat_00057.1.el7eap.noarch as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 7 Server; eap7-activemq-artemis-jms-server-0:2.16.0-22.redhat_00057.1.el7eap.noarch as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 7 Server; eap7-activemq-artemis-journal-0:2.16.0-22.redhat_00057.1.el7eap.noarch as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 7 Server; eap7-activemq-artemis-ra-0:2.16.0-22.redhat_00057.1.el7eap.noarch as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 7 Server; eap7-activemq-artemis-selector-0:2.16.0-22.redhat_00057.1.el7eap.noarch as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 7 Server; eap7-activemq-artemis-server-0:2.16.0-22.redhat_00057.1.el7eap.noarch as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 7 Server; eap7-activemq-artemis-service-extensions-0:2.16.0-22.redhat_00057.1.el7eap.noarch as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 7 Server; eap7-activemq-artemis-tools-0:2.16.0-22.redhat_00057.1.el7eap.noarch as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 7 Server; eap7-glassfish-jsf-0:2.3.14-11.SP11_redhat_00001.1.el7eap.noarch as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 7 Server; eap7-glassfish-jsf-0:2.3.14-11.SP11_redhat_00001.1.el7eap.src as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 7 Server; eap7-ironjacamar-0:1.5.26-2.Final_redhat_00001.1.el7eap.noarch as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 7 Server; eap7-ironjacamar-0:1.5.26-2.Final_redhat_00001.1.el7eap.src as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 7 Server; eap7-ironjacamar-common-api-0:1.5.26-2.Final_redhat_00001.1.el7eap.noarch as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 7 Server; eap7-ironjacamar-common-impl-0:1.5.26-2.Final_redhat_00001.1.el7eap.noarch as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 7 Server; eap7-ironjacamar-common-spi-0:1.5.26-2.Final_redhat_00001.1.el7eap.noarch as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 7 Server; eap7-ironjacamar-core-api-0:1.5.26-2.Final_redhat_00001.1.el7eap.noarch as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 7 Server; eap7-ironjacamar-core-impl-0:1.5.26-2.Final_redhat_00001.1.el7eap.noarch as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 7 Server; eap7-ironjacamar-deployers-common-0:1.5.26-2.Final_redhat_00001.1.el7eap.noarch as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 7 Server; eap7-ironjacamar-jdbc-0:1.5.26-2.Final_redhat_00001.1.el7eap.noarch as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 7 Server; eap7-ironjacamar-validator-0:1.5.26-2.Final_redhat_00001.1.el7eap.noarch as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 7 Server; eap7-jackson-annotations-0:2.18.8-1.redhat_00003.1.el7eap.noarch as a component of Red Hat JBoss EAP 7.4 ELS for RHEL 7 Server; and 72 more
Action
Before applying the update, make sure all previously released errata relevant to your system have been applied. Also, back up your existing installation, including all applications, configuration files, databases and database settings. For details on how to apply this update, refer to: https://access.redhat.com/articles/11258
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04

Evidence and provenance

Published 11 Aug 2026 · Last source change 24 Aug 2026, 11:38 UTC · CWE-295 · Improper Certificate Validation

CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2026-55981
Product sourceVendor CSAF · Red Hat Product Security
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD awaiting enrichment

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates →

No material field changes have been recorded since change tracking began. Routine source refreshes and cosmetic edits are intentionally excluded.

Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Fixed release or patch reference recorded
ENISA EUVD · EUVD-2026-55981↗Vendor CSAF · Red Hat Product Security↗CVE authority or vendor reference↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2026-15554 · cve.blacktree.nl