CVE-2025-12543 | Undertow-core: undertow http server fails to reject malformed host headers leading to potential cache poisoning and ssrf

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: 2026-01-07 Last update: 2026-03-18 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2025-12543 is rated Moderate Risk (61.8/100): CVSS Critical severity, with medium exploitation likelihood (EPSS 1.18%). EPSS rose +1.15% over the last day, indicating growing attacker interest. Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2025-12543

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.03% 1.18% +1.15%
2 2026-06-05 0.05% 0.03% -0.02%
3 2026-05-09 — 0.05% —

Full EPSS history (9 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-12543

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.6 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:L Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
 2.8 6.0 [email protected]
9.6 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.8 6.0 [email protected]

Weakness enumeration for CVE-2025-12543

GitHub Security Advisory for CVE-2025-12543

GHSA-j382-5jj3-vw4j · Severity: critical · Ecosystem: maven — Undertow HTTP server core doesn't properly validate the Host header in incoming HTTP requests

OS Trackers for CVE-2025-12543

vendor priority summary link
debian not yet assigned CVE-2025-12543 not yet assigned priority: Debian including 1 source packages (undertow), 2 status rows across 2 suites (forky, sid): open 2. https://security-tracker.debian.org/tracker/CVE-2025-12543
redhat high — https://access.redhat.com/security/cve/CVE-2025-12543
ubuntu high CVE-2025-12543 high priority: Ubuntu including 1 source packages (undertow), 8 status rows across 8 suites (bionic, focal, jammy, noble, plucky, questing, upstream, xenial): released 5, ignored 1, needed 1, needs-triage 1. https://ubuntu.com/security/CVE-2025-12543

Affected software / configurations for CVE-2025-12543

Vendor Product Version Raw CPE
redhat build_of_apache_camel < 4.14.4 cpe:2.3:a:redhat:build_of_apache_camel:*:*:*:*:*:spring_boot:*:*
redhat data_grid 8.0 cpe:2.3:a:redhat:data_grid:8.0:*:*:*:*:*:*:*
redhat fuse 7.0.0 cpe:2.3:a:redhat:fuse:7.0.0:*:*:*:*:*:*:*
redhat jboss_enterprise_application_platform >= 8.0, < 8.0.12 cpe:2.3:a:redhat:jboss_enterprise_application_platform:*:*:*:*:*:*:*:*
redhat jboss_enterprise_application_platform >= 8.1.0, < 8.1.3 cpe:2.3:a:redhat:jboss_enterprise_application_platform:*:*:*:*:*:*:*:*
redhat jboss_enterprise_application_platform — cpe:2.3:a:redhat:jboss_enterprise_application_platform:-:*:*:*:text-only:*:*:*
redhat jboss_enterprise_application_platform 7.0.0 cpe:2.3:a:redhat:jboss_enterprise_application_platform:7.0.0:*:*:*:*:*:*:*
redhat jboss_enterprise_application_platform_expansion_pack — cpe:2.3:a:redhat:jboss_enterprise_application_platform_expansion_pack:-:*:*:*:*:*:*:*
redhat process_automation 7.0 cpe:2.3:a:redhat:process_automation:7.0:*:*:*:*:*:*:*
redhat single_sign-on 7.0 cpe:2.3:a:redhat:single_sign-on:7.0:*:*:*:*:*:*:*
redhat undertow < 2.2.39 cpe:2.3:a:redhat:undertow:*:*:*:*:*:*:*:*
redhat undertow >= 2.3.0, < 2.3.21 cpe:2.3:a:redhat:undertow:*:*:*:*:*:*:*:*

References for CVE-2025-12543

URL Tags
https://access.redhat.com/errata/RHSA-2026:0383 Vendor Advisory
https://access.redhat.com/errata/RHSA-2026:0384 Vendor Advisory
https://access.redhat.com/errata/RHSA-2026:0386 Vendor Advisory
https://access.redhat.com/errata/RHSA-2026:3889 Vendor Advisory
https://access.redhat.com/errata/RHSA-2026:3890 Vendor Advisory
https://access.redhat.com/errata/RHSA-2026:3891 Vendor Advisory
https://access.redhat.com/errata/RHSA-2026:3892 Vendor Advisory
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 Vendor Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2408784 Issue Tracking Vendor Advisory
cvelogic Threat Intelligence