Vulnary
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Critical· 9.6

CVE-2025-12543

A flaw in the Undertow HTTP server core allows attackers to send HTTP requests with malformed Host headers that are not properly validated. This can lead to cache poisoning, internal network scans, or session hijacking. The vulnerability is present in several Red Hat products that use Undertow.

publishedJan 7, 2026
last modifiedJul 28, 2026
sourcesNVD
severity · cvss
9.6
critical · how bad it is
exploitation · epss
1%
65th percentile · chance of exploitation in 30 days
(ai-assisted) A model wrote this summary from the official data, so double-check it against the source before you act on it. Read the official advisory →
auto-deletes from the system
counting…on Sep 7, 2026

No official fix yet. If none appears within 45 days of first tracking, this entry is removed automatically.

01

Who is affected

redhat build_of_apache_camel, redhat data_grid 8.0, redhat fuse 7.0.0, redhat jboss_enterprise_application_platform, redhat jboss_enterprise_application_platform -, redhat jboss_enterprise_application_platform 7.0.0, redhat jboss_enterprise_application_platform_expansion_pack -, redhat process_automation 7.0, redhat single_sign-on 7.0, redhat undertow

02

Real-world impact

An attacker could poison application caches, discover internal network services, or hijack user sessions by exploiting the unchecked Host header.

03

Why this severity

The CVSS score of 9.6 reflects a network‑based attack (AV:N) that requires low complexity (AC:L) and no privileges (PR:N). The vulnerability changes scope (S:C) and grants high confidentiality and integrity impact (C:H, I:H) while only affecting availability at a low level (A:L). User interaction is required (UI:R) because the attacker must send a crafted HTTP request.

04

What to do about it

no official fix yet

No official fix or mitigation is documented in the sources yet. Monitor the vendor advisory and apply the patch as soon as it is released.

No fix documented in sources

05

Timeline

  1. Jan 7, 2026 · Jan 7, 2026
    Published
    Disclosed and added to the National Vulnerability Database.
  2. Jul 28, 2026 · 8d ago
    Advisory updated
    The NVD record was last revised.
06

How it’s attacked

Attack vectorNetwork (remote)
Attack complexityLow
Privileges requiredNone
User interactionRequired
ScopeChanged
Confidentiality impactHigh
Integrity impactHigh
Availability impactLow
07

References & advisories

NVD advisory ↗Search advisories ↗
(ai-assisted) A model wrote this summary from the official data, so double-check it against the source before you act on it. Read the official advisory →