Is CVE-2026-42253 in the CISA KEV catalog?

No. CVE-2026-42253 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-42253?

CVE-2026-42253 has a CVSS v3 base score of 6.1 (MEDIUM).

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

CVE-2026-42253 has an EPSS score of 1.11% (62th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-42253?

Upgrade activemq to 6.2.6 or later. Fixes are available for 2 affected products.

CVE & CISA-KEV Catalog

CVE-2026-42253

MEDIUM

6.1

CVSS v3

NVD

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.

CWE-79Cross-Site Scripting (XSS)

How to fix

Remediation Available

activemqNVD

Affected:>= 6.0.0, < 6.2.6Fixed in:6.2.6CVE-2026-42253derived from NVD

activemq webNVD

Affected:>= 6.0.0, < 6.2.6Fixed in:6.2.6CVE-2026-42253derived from NVD

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionRequired

ScopeChanged

Impact

ConfidentialityLow

IntegrityLow

AvailabilityNone

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

Exploit Intelligence

1.11%probability of exploitation in 30 days

62ndpercentile

Moderate risk: more likely to be exploited than 62% of all known CVEs.

References

Vendor Advisory1

lists.apache.org

Third-Party Advisory1

openwall.com

Related Vulnerabilities

Other CWE-79 (Cross-Site Scripting (XSS)) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2020-11022	Medium	6.9	99%	-	Fix
CVE-2019-3929	Critical	9.8	99%	KEV	Fix
CVE-2020-9496	Medium	6.1	99%	-	-
CVE-2023-28341	Medium	6.1	99%	-	Fix
CVE-2018-12998	Medium	6.1	98%	-	-
CVE-2025-4123	High	7.6	98%	-	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-06-01.