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    CVE-2025-12543

    A flaw was found in the Undertow HTTP server core, which is used in WildFly, JBoss EAP, and other Java applications. The Undertow library fails to properly validate the Host header in incoming HTTP requests.As a result, requests containing malformed or malicious Host headers are processed without rejection, enabling attackers to poison caches, perform internal network scans, or hijack user sessions.

    Published:Jan 7, 2026
    Last Modified:Aug 19, 2026
    EPS:Jan 7, 2026
    EPSS Score:0.012
    CVSS Score:9.6

    Affected Products

    Vendor
    Redhat
    Product
    Apache Camel Hawtio
    Vendor
    Redhat
    Product
    Apache Camel Spring Boot
    Vendor
    Redhat
    Product
    Build Of Apache Camel
    Vendor
    Redhat
    Product
    Data Grid
    Vendor
    Redhat
    Product
    Enterprise Linux
    Vendor
    Redhat
    Product
    Fuse
    Vendor
    Redhat
    Product
    Jboss Data Grid
    Vendor
    Redhat
    Product
    Jboss Enterprise Application Platform
    Vendor
    Redhat
    Product
    Jboss Enterprise Application Platform Els
    Vendor
    Redhat
    Product
    Jboss Enterprise Application Platform Eus
    Vendor
    Redhat
    Product
    Jboss Enterprise Application Platform Expansion Pack
    Vendor
    Redhat
    Product
    Jboss Enterprise Bpms Platform
    Vendor
    Redhat
    Product
    Jboss Fuse
    Vendor
    Redhat
    Product
    Jbosseapxp
    Vendor
    Redhat
    Product
    Process Automation
    Vendor
    Redhat
    Product
    Red Hat Single Sign On
    Vendor
    Redhat
    Product
    Single Sign-on
    Vendor
    Redhat
    Product
    Undertow

    Exploits

    https://github.com/kavin71725/CVE-2025-12543-Fix-for-Wildfly

    Common Weakness Enumeration

    CWE-20 Improper Input Validation

    Common Attack Pattern Enumeration and Classification (CAPEC)

    CAPEC-10 Buffer Overflow via Environment Variables
    CAPEC-101 Server Side Include (SSI) Injection
    CAPEC-104 Cross Zone Scripting
    CAPEC-108 Command Line Execution through SQL Injection
    CAPEC-109 Object Relational Mapping Injection
    CAPEC-110 SQL Injection through SOAP Parameter Tampering
    CAPEC-120 Double Encoding
    CAPEC-13 Subverting Environment Variable Values
    CAPEC-135 Format String Injection
    CAPEC-136 LDAP Injection
    CAPEC-14 Client-side Injection-induced Buffer Overflow
    CAPEC-153 Input Data Manipulation
    CAPEC-182 Flash Injection
    CAPEC-209 XSS Using MIME Type Mismatch
    CAPEC-22 Exploiting Trust in Client
    CAPEC-23 File Content Injection
    CAPEC-230 Serialized Data with Nested Payloads
    CAPEC-231 Oversized Serialized Data Payloads
    CAPEC-24 Filter Failure through Buffer Overflow
    CAPEC-250 XML Injection
    CAPEC-261 Fuzzing for garnering other adjacent user/sensitive data
    CAPEC-267 Leverage Alternate Encoding
    CAPEC-28 Fuzzing
    CAPEC-3 Using Leading 'Ghost' Character Sequences to Bypass Input Filters
    CAPEC-31 Accessing/Intercepting/Modifying HTTP Cookies
    CAPEC-42 MIME Conversion
    CAPEC-43 Exploiting Multiple Input Interpretation Layers
    CAPEC-45 Buffer Overflow via Symbolic Links
    CAPEC-46 Overflow Variables and Tags
    CAPEC-47 Buffer Overflow via Parameter Expansion
    CAPEC-473 Signature Spoof
    CAPEC-52 Embedding NULL Bytes
    CAPEC-53 Postfix, Null Terminate, and Backslash
    CAPEC-588 DOM-Based XSS
    CAPEC-63 Cross-Site Scripting (XSS)
    CAPEC-64 Using Slashes and URL Encoding Combined to Bypass Validation Logic
    CAPEC-664 Server Side Request Forgery
    CAPEC-67 String Format Overflow in syslog()
    CAPEC-7 Blind SQL Injection
    CAPEC-71 Using Unicode Encoding to Bypass Validation Logic
    CAPEC-72 URL Encoding
    CAPEC-73 User-Controlled Filename
    CAPEC-78 Using Escaped Slashes in Alternate Encoding
    CAPEC-79 Using Slashes in Alternate Encoding
    CAPEC-8 Buffer Overflow in an API Call
    CAPEC-80 Using UTF-8 Encoding to Bypass Validation Logic
    CAPEC-81 Web Server Logs Tampering
    CAPEC-83 XPath Injection
    CAPEC-85 AJAX Footprinting
    CAPEC-88 OS Command Injection
    CAPEC-9 Buffer Overflow in Local Command-Line Utilities

    Related CVEs

    CVE-2026-80219 (CVSS 8.7) — A flaw was found in hawtio-operator. When deploying Hawtio in cluster mode, the operator creates a cluster-sco…
    CVE-2026-78234 (CVSS 9.9) — A flaw was found in hawtio-operator. The operator reads the OpenShift Service CA private signing key from the …
    CVE-2026-77968 (CVSS 8.2) — A flaw was found in hawtio-operator. The operator's ClusterRole grants secrets: [create, get, list, update, wa…
    CVE-2026-5680 (CVSS 7.5) — A flaw was found in Undertow. A remote attacker could exploit this vulnerability by sending specially crafted …
    CVE-2026-14180 (CVSS 5.3) — A flaw was found in the ChunkReader component of the Undertow HTTP server, which is used by WildFly and JBoss …
    CVE-2026-28369 (CVSS 8.7) — A flaw was found in Undertow. When Undertow receives an HTTP request where the first header line starts with o…
    CVE-2026-28367 (CVSS 8.7) — A flaw was found in Undertow. A remote attacker can exploit this vulnerability by sending `\r\r\r` as a header…
    CVE-2026-28368 (CVSS 8.7) — A flaw was found in Undertow. This vulnerability allows a remote attacker to construct specially crafted reque…
    CVE-2024-3884 (CVSS 7.5) — A flaw was found in Undertow that can cause remote denial of service attacks. When the server uses the FormEnc…
    CVE-2025-9784 (CVSS 7.5) — A flaw was found in Undertow where malformed client requests can trigger server-side stream resets without tri…

    References

    https://access.redhat.com/errata/RHSA-2026:0383
    https://access.redhat.com/errata/RHSA-2026:0384
    https://access.redhat.com/errata/RHSA-2026:0386
    https://access.redhat.com/errata/RHSA-2026:33371
    https://access.redhat.com/errata/RHSA-2026:33372
    https://access.redhat.com/errata/RHSA-2026:3889
    https://access.redhat.com/errata/RHSA-2026:3890
    https://access.redhat.com/errata/RHSA-2026:3891
    https://access.redhat.com/errata/RHSA-2026:3892
    https://access.redhat.com/errata/RHSA-2026:4915
    https://access.redhat.com/errata/RHSA-2026:4916
    https://access.redhat.com/errata/RHSA-2026:4917
    https://access.redhat.com/errata/RHSA-2026:4924
    https://access.redhat.com/security/cve/CVE-2025-12543
    https://bugzilla.redhat.com/show_bug.cgi?id=2408784
    https://access.redhat.com/errata/RHSA-2026:0383
    https://access.redhat.com/errata/RHSA-2026:0384
    https://access.redhat.com/errata/RHSA-2026:0386
    https://access.redhat.com/errata/RHSA-2026:33371
    https://access.redhat.com/errata/RHSA-2026:33372
    https://access.redhat.com/errata/RHSA-2026:3889
    https://access.redhat.com/errata/RHSA-2026:3890
    https://access.redhat.com/errata/RHSA-2026:3891
    https://access.redhat.com/errata/RHSA-2026:3892
    https://access.redhat.com/errata/RHSA-2026:4915
    https://access.redhat.com/errata/RHSA-2026:4916
    https://access.redhat.com/errata/RHSA-2026:4917
    https://access.redhat.com/errata/RHSA-2026:4924
    https://access.redhat.com/security/cve/CVE-2025-12543
    https://bugzilla.redhat.com/show_bug.cgi?id=2408784
    https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-12543.json

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High