CVE-2026-42253Network attack vector

Response header injection via unchecked JMS properties

Published Jun 1, 2026 · Updated Jun 1, 2026

HTTP response header injection in Apache ActiveMQ and ActiveMQ Web before 5.19.7 and 6.0.0 through 6.2.5 allows remote attackers to alter responses. MessageServlet copies every property of a returned JMS message directly into an HTTP response header without validation, allowing supplied properties to overwrite or inject security headers. The attack requires user interaction and a reachable, enabled servlet; injected security headers can change browser handling of the response.

CVSS severity6.1
Medium
EPSS probability1.11%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

HTTP response header injection in Apache ActiveMQ and ActiveMQ Web before 5.19.7 and 6.0.0 through 6.2.5 allows remote attackers to alter responses. MessageServlet copies every property of a returned JMS message directly into an HTTP response header without validation, allowing supplied properties to overwrite or inject security headers. The attack requires user interaction and a reachable, enabled servlet; injected security headers can change browser handling of the response.

The record

CVE
CVE-2026-42253
Published
Jun 1, 2026
Updated
Jun 1, 2026
Vendor
The Apache Software Foundation
Product
Apache ActiveMQ Web
Classifications
CWE-79
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 1, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 1, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <5.19.7
  2. Affected versionversion=6.0.0 <6.2.6

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Apache Software Foundation · Apache ActiveMQ Webversion=0 <5.19.7; version=6.0.0 <6.2.6
The Apache Software Foundation · Apache ActiveMQversion=0 <5.19.7; version=6.0.0 <6.2.6

Published CVSS scores

6.1CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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