CVE-2025-12543: A flaw was found in the Undertow HTTP server core, which is used in WildFly, JBoss EAP, and other Java applica

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CRITICAL 9.6WATCHLISTUPGRADEDOWNGRADEDOWNGRADE

CVE-2025-12543 is a critical-severity flaw (CVSS 9.6) affecting build of apache camel, data grid, fuse. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

Critical severity
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	9.6 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	1.3% (top 29%)
CISA exploited list	No
Weakness	CWE-20
Published	2026-01-07
Last modified	2026-10-14

Publisher (CNA): Red Hat, Inc. · Vendor: redhat

Last updated 2026-10-14 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-01-07 17:15 UTCPublished CVE record published
2026-10-14 17:17 UTCUpdated Record last modified

redhat build of apache camel UPGRADE

Affected: < 4.14.4

Fixed in: 4.14.4

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy build-of-apache-camel || rpm -q build-of-apache-camel || build-of-apache-camel --version

2. UPGRADE to 4.14.4 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade build-of-apache-camel

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade build-of-apache-camel

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

redhat data grid DOWNGRADE

Affected: 8.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 8.0

1. Check installed version

apt-cache policy data-grid || rpm -q data-grid || data-grid --version

2. No fixed release: DOWNGRADE to a release before 8.0 (Debian / Ubuntu)

apt-cache madison data-grid sudo apt install data-grid=<VERSION_BEFORE_8.0> sudo apt-mark hold data-grid

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list data-grid sudo dnf downgrade data-grid-<VERSION_BEFORE_8.0> sudo dnf versionlock add data-grid

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

redhat fuse DOWNGRADE

Affected: 7.0.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 7.0.0

1. Check installed version

apt-cache policy fuse || rpm -q fuse || fuse --version

2. No fixed release: DOWNGRADE to a release before 7.0.0 (Debian / Ubuntu)

apt-cache madison fuse sudo apt install fuse=<VERSION_BEFORE_7.0.0> sudo apt-mark hold fuse

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list fuse sudo dnf downgrade fuse-<VERSION_BEFORE_7.0.0> sudo dnf versionlock add fuse

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

redhat jboss enterprise application platform UPGRADE

Affected: >= 8.0 and < 8.0.12 · >= 8.1.0 and < 8.1.3 · all versions · 7.0.0

Fixed in: 8.0.12, 8.1.3

Safe to downgrade to: a release before 7.0.0

1. Check installed version

apt-cache policy jboss-enterprise-application-platform || rpm -q jboss-enterprise-application-platform || jboss-enterprise-application-platform --version

2. UPGRADE to 8.0.12 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade jboss-enterprise-application-platform

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade jboss-enterprise-application-platform

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 7.0.0 (Debian / Ubuntu)

apt-cache madison jboss-enterprise-application-platform sudo apt install jboss-enterprise-application-platform=<VERSION_BEFORE_7.0.0> sudo apt-mark hold jboss-enterprise-application-platform

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list jboss-enterprise-application-platform sudo dnf downgrade jboss-enterprise-application-platform-<VERSION_BEFORE_7.0.0> sudo dnf versionlock add jboss-enterprise-application-platform

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

redhat jboss enterprise application platform expansion pack MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy jboss-enterprise-application-platform-expansion-pack || rpm -q jboss-enterprise-application-platform-expansion-pack || jboss-enterprise-application-platform-expansion-pack --version

No fixed or unaffected release known

Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.

redhat process automation DOWNGRADE

Affected: 7.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 7.0

1. Check installed version

apt-cache policy process-automation || rpm -q process-automation || process-automation --version

2. No fixed release: DOWNGRADE to a release before 7.0 (Debian / Ubuntu)

apt-cache madison process-automation sudo apt install process-automation=<VERSION_BEFORE_7.0> sudo apt-mark hold process-automation

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list process-automation sudo dnf downgrade process-automation-<VERSION_BEFORE_7.0> sudo dnf versionlock add process-automation

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Exact fixes by distribution

A distro patch exists: prefer upgrading over downgrading.

Maven · io.undertow:undertow-core · NO FIX YET · vulnerable: = 2.4.0.Alpha1 · source

Fedora ELN · openldap · FIXED · 2.6.16-1.eln159 · FEDORA-2026-4b30c86326 · source

sudo dnf upgrade --advisory=FEDORA-2026-4b30c86326

Fedora 46 · php-pecl-yac · FIXED · 3.0.1-2.fc46 · FEDORA-2026-5f43289aa2 · source

sudo dnf upgrade --advisory=FEDORA-2026-5f43289aa2

Ubuntu 20.04 · undertow · FIXED · 2.0.29-1ubuntu0.1~esm1

sudo apt update && sudo apt install --only-upgrade undertow dpkg --compare-versions "$(dpkg-query -W -f='${Version}' undertow)" ge "2.0.29-1ubuntu0.1~esm1" && echo PATCHED || echo STILL-VULNERABLE

Ubuntu 22.04 · undertow · FIXED · 2.2.16-1ubuntu0.1~esm1

sudo apt update && sudo apt install --only-upgrade undertow dpkg --compare-versions "$(dpkg-query -W -f='${Version}' undertow)" ge "2.2.16-1ubuntu0.1~esm1" && echo PATCHED || echo STILL-VULNERABLE

Ubuntu 24.04 · undertow · FIXED · 2.3.8-2ubuntu0.1~esm1

sudo apt update && sudo apt install --only-upgrade undertow dpkg --compare-versions "$(dpkg-query -W -f='${Version}' undertow)" ge "2.3.8-2ubuntu0.1~esm1" && echo PATCHED || echo STILL-VULNERABLE

RHEL 10 · moditect · NOT AFFECTED

RHEL 8 · pki-core:10.6/resteasy · NOT AFFECTED

RHEL 8 · pki-deps:10.6/resteasy · NOT AFFECTED

RHEL 9 · resteasy · NOT AFFECTED

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

GitHub PoC: kavin71725/CVE-2025-12543-Fix-for-Wildfly (0 stars)

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2025-12543?

build of apache camel: upgrade to 4.14.4; data grid: downgrade or apply the listed mitigation; fuse: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2025-12543 being exploited?

CVE-2025-12543 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2025-12543 affect?

CVE-2025-12543 affects build of apache camel, data grid, fuse. Severity is critical (CVSS 9.6). 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

How urgent is CVE-2025-12543?

Priority 56/100. Critical severity; On your watchlist

Software pages

Java vulnerabilities · JBoss and WildFly vulnerabilities

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References

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