CVE-2026-34197
CVE-2026-34197 is a security flaw in Apache ActiveMQ, software that passes messages between business applications. Someone who already has a way in can use Apache ActiveMQ to run their own code. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 16 Apr 2026.[1]
Apache ActiveMQ is business software or equipment. Most families won’t have it, but attackers break into it to get inside companies, and from there to what those companies hold about their customers, patients and staff. Fixed in version 5.19.4 and 6.2.3.
Description
CISA calls it an improper input validation in Apache ActiveMQ. In its words: “Apache ActiveMQ contains an improper input validation vulnerability that allows for code injection.”[1]
The CVE record adds: “Improper Input Validation, Improper Control of Generation of Code ('Code Injection') vulnerability in Apache ActiveMQ Broker, Apache ActiveMQ. Apache ActiveMQ Classic exposes the Jolokia JMX-HTTP bridge at /api/jolokia/ on the web console. The default Jolokia access policy permits exec operations on all ActiveMQ MBeans (org.apache.activemq:*), including BrokerService.addNetworkConnector(String) and BrokerService.addConnector(String). An authenticated attacker can invoke these operations with a crafted discovery URI that triggers the VM transport's brokerConfig parameter to load a remote Spring XML application context using ResourceXmlApplicationContext. Because Spring's ResourceXmlApplicationContext instantiates all singleton beans before the BrokerService validates the configuration, arbitrary code execution occurs on the broker's JVM through bean factory methods…”[2]
The underlying weakness is improper input validation (CWE-20), code injection (CWE-94), in MITRE’s list of common software weaknesses.
It scores 8.8 out of 10 on the Common Vulnerability Scoring System, which rates it high, scored by the organisation that published the CVE using CVSS 3.1.[2]
Affected versions
NVD’s record lists these fixed versions: in each line, everything before the version shown is affected.[2]
| Product | Fixed in |
|---|---|
| Apache ActiveMQ Broker | 5.19.4 |
| Apache ActiveMQ Broker | 6.2.3 |
| Apache ActiveMQ All | 5.19.4 |
| Apache ActiveMQ All | 6.2.3 |
| Apache ActiveMQ | 5.19.4 |
| Apache ActiveMQ | 6.2.3 |
Most families won’t have Apache ActiveMQ; it’s for whoever looks after IT at work.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 16 Apr 2026, 9 days after it was made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 30 Apr 2026 to fix it.[1]
FIRST’s Exploit Prediction Scoring System, which estimates how likely a flaw is to be used in attacks in the next 30 days from what it sees across the internet, puts it at 98%. That’s in the top 1% of the flaws it scores.[4]
CISA assesses it as not automatable: each attack takes some work.
CISA doesn’t say who was attacked, or how.
Fix
Apache has published a fix or advice.[3] CISA’s required action: “Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.”[1]
- Check whether you use it.Apache ActiveMQ is business software or equipment, so most families won’t have it. If you run a business, or work from home on company equipment, ask whoever looks after your IT.
- Send this page to your IT person.Ask them to confirm it’s fixed (fixed in version 5.19.4 and 6.2.3), or not in use. CISA gave US government agencies until 30 Apr 2026 to fix it.
- If it can’t be fixed, take it offline.CISA’s advice when there’s no fix is to stop using the product, or take it off the internet, until there is one.
You can’t fix someone else’s server, but you can watch for what follows a break-in like this: a breach notice, a password reset you didn’t ask for, or a scam message that knows things it shouldn’t. HARD watches for those for you and your family.
Timeline
| Date | Event |
|---|---|
| The flaw is made public in the National Vulnerability Database, with a severity score of 8.8.[2] | |
| CISA adds it to its catalog of flaws known to be used in attacks.[1] | |
| CISA’s deadline for US government agencies to fix it.[1] | |
| FIRST puts the odds of it being used in attacks in the next 30 days at 98%.[4] |
See also
Other Apache ActiveMQ flaws
- CVE-2023-46604: deserialization of untrusted data ·
- CVE-2016-3088: improper input validation ·
Other Apache flaws
- CVE-2016-3081, Apache Struts: command injection ·
- CVE-2026-34486, Apache Tomcat: missing encryption of sensitive data ·
- CVE-2024-38475, Apache HTTP Server: improper escaping of output ·
- CVE-2025-24813, Apache Tomcat: path equivalence ·
- CVE-2024-45195, Apache OFBiz: forced browsing ·
Other improper input validation flaws
- CVE-2026-93952, Arista VeloCloud Orchestrator: improper input validation ·
- CVE-2019-1068, Microsoft SQL Server: remote code execution ·
- CVE-2026-12569, PTC Windchill and FlexPLM: improper input validation ·
- CVE-2026-34910, Ubiquiti UniFi OS: improper input validation ·
- CVE-2026-6973, Ivanti Endpoint Manager Mobile (EPMM): improper input validation ·
Every Apache flaw on CISA’s list · Everything added in April 2026
References
- ^ Cybersecurity and Infrastructure Security Agency. “Apache ActiveMQ Improper Input Validation Vulnerability”. Known Exploited Vulnerabilities Catalog, added 16 Apr 2026.
- ^ National Institute of Standards and Technology. “CVE-2026-34197 Detail”. National Vulnerability Database, published 7 Apr 2026.
- ^ Apache. Advisories and fixes: activemq.apache.org.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.983, percentile 99.9, 31 Oct 2026.
- CVE Program. “CVE-2026-34197”. The official CVE record.
This article is built from CISA’s catalog (version 2026.10.30), NVD’s record and FIRST’s scores, kept in HARD’s database and checked every morning. The plain English is HARD’s.