How severe is CVE-2026-42253?

CVE-2026-42253 has a CVSS score of 6.1/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2026-42253?

CVE-2026-42253 affects the following packages: org.apache.activemq:apache-activemq (Maven), org.apache.activemq:apache-activemq (Maven), org.apache.activemq:activemq-web (Maven), org.apache.activemq:activemq-web (Maven). Ecosystems affected: Maven.

How do I fix CVE-2026-42253?

Update org.apache.activemq:apache-activemq to 5.19.7 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-42253 is resolved across your whole dependency graph.

How do I detect CVE-2026-42253 in my Maven dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.apache.activemq:apache-activemq, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-42253 if there is no patch (or I can't update yet)?

Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Is CVE-2026-42253 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-42253 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-42253?

CVE-2026-42253 has an EPSS (Exploit Prediction Scoring System) score of 0.7%, placing it in the 51th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-42253?

CVE-2026-42253 is classified as Cross-site Scripting (XSS) (CWE-79). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2026-42253 published, and has it been updated?

CVE-2026-42253 was published on June 1, 2026 and was last updated on October 8, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

☕

☕ Maven

Not in CISA KEV

MEDIUM severity

CVE-2026-42253 — apache-activemq

MEDIUM

CVE-2026-42253 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in org.apache.activemq:apache-activemq. A fix is available for org.apache.activemq:apache-activemq — see the affected versions and patch details below.

Apache ActiveMQ, Apache ActiveMQ Web: HTTP Response Header Injection via JMS Message Properties

Also known asBIT-activemq-2026-42253GHSA-8wm6-6fqh-phmc

Published

Jun 1, 2026

Updated

Oct 8, 2026

Affected

4 pkgs

Patched

4 / 4

Exploits

None indexed

Exploitation data as of Oct 13, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-42253.

EPSS Exploitation Probability

via FIRST.org ↗

0.7%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs51th percentile — riskier than 51% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2026-42253 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 386,684 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

4 pkgs affected

☕org.apache.activemq:apache-activemq☕org.apache.activemq:apache-activemq☕org.apache.activemq:activemq-web☕org.apache.activemq:activemq-web

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.

Description

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in Apache ActiveMQ, Apache ActiveMQ Web.

The MessageServlet in the ActiveMQ web console API copies every JMS message property into an HTTP response header without any validation. This can allow overwriting and injecting security headers by setting them on JMS messages that are returned by the servlet.

This issue affects Apache ActiveMQ: before 5.19.7, from 6.0.0 before 6.2.6; Apache ActiveMQ Web: before 5.19.7, from 6.0.0 before 6.2.6.

Users are recommended to upgrade to version 5.19.7 or 6.2.6, which fixes the issue. The MessageServlet has now been deprecated and disabled by default.

Affected Packages

4 total 4 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`org.apache.activemq:apache-activemq`	all versions	5.19.7`org.apache.activemq:apache-activemq:5.19.7`
☕Maven	`org.apache.activemq:apache-activemq`	≥ 6.0.0&&< 6.2.6	6.2.6`org.apache.activemq:apache-activemq:6.2.6`
☕Maven	`org.apache.activemq:activemq-web`	all versions	5.19.7`org.apache.activemq:activemq-web:5.19.7`
☕Maven	`org.apache.activemq:activemq-web`	≥ 6.0.0&&< 6.2.6	6.2.6`org.apache.activemq:activemq-web:6.2.6`

Affected Products

2 products · 4 configurations

Application

activemqapache

≥ 6.0.0 && < 6.2.6

range

Application

activemq webapache

≥ 6.0.0 && < 6.2.6

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.apache.activemq:apache-activemq, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update org.apache.activemq:apache-activemq to 5.19.7 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-42253 is resolved across your whole dependency graph.
Workarounds
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Frequently Asked Questions

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in Apache ActiveMQ, Apache ActiveMQ Web. The MessageServlet in the ActiveMQ web console API copies every JMS message property into an HTTP response header without any validation. This can allow overwriting and injecting security headers by setting them on JMS messages that are returned by the servlet. This issue affects Apache ActiveMQ: before 5.19.7, from 6.0.0 before 6.2.6; Apache ActiveMQ Web: before 5.19.7, from 6.0.0 before 6.2.6. Users are recommended to upgrade to version 5.19.7 or 6.2.

O3 Security · Impact-Aware SCA

Is CVE-2026-42253 in your dependencies?

Find it across Maven, including transitive dependencies.

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CVSS Score

6.1/10CVSS v3 base

Vector breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

None

Raw vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

CWE Classification

CWE-79Cross-site Scripting (XSS)

Weaponization

No known public exploit tooling found.

OpenSSF Scorecard

Package health score

activemq

7.0/10

Maintained10/10

Code-Review10/10

Branch-ProtectionN/A

Assessed Oct 12, 2026

Timeline

Disclosed

Jun 1, 2026

Last updated

Oct 8, 2026

Identifiers

CVE-2026-42253

GHSA-8wm6-6fqh-phmc

BIT-activemq-2026-42253

References

Advisorygithub.com Advisorylists.apache.org Advisorynvd.nist.gov Webopenwall.com Webrepo.maven.apache.org Packagegithub.com

Related vulnerabilities

This CVE is medium severity; 8 of 8 other CVEs affecting apache-activemq are rated as high or higher (top: high).

CVE-2026-49157CVE-2026-46605CVE-2026-49270CVE-2026-42588CVE-2026-45505CVE-2026-41043CVE-2026-41044CVE-2026-40466

Provenance

Sources

OSV.devNVDFIRST.org (EPSS)

Last verifiedOct 8, 2026