Summary
Workarounds
When duplicating a duplicated context, the following code can be done to avoid the potential leak:
((ContextInternal) VertxContext.getRootContext(ctx)).duplicate()
This workaround would not be required once the Vert.x version containing the fix will be included. Note that the workaround would still work.
References
This issue have been reported in https://github.com/quarkusio/quarkus/issues/48227.
Impact
Vert.x 4.5.12 has changed the semantics of the duplication of duplicated context.
Duplicated context is an object used to propagate data through a processing (synchronous or asynchronous). Each "transaction" or "processing" runs on its own isolated duplicated context.
Initially, duplicating a duplicated context was creating a fresh (empty) new context, meaning that the new duplicated context can be used to managed a separated transaction.
In Vert.x 4.5.12, this semantics has changed, and since the content of the parent duplicated context is copied into the new one, potentially leaking data.
This CVE is especially for Quarkus as Quarkus extensively uses the Vert.x duplicated context to implement context propagation. With the new semantic data from one transaction can leak to the data from another transaction. From a Vert.x point of view, this new semantic clarifies the behavior.
A significant amount of data is stored in the duplicated context, including request scope, security details, and metadata. Duplicating a duplicated context is rather rare and is only done in a few places:
- Quarkus REST Client when using OTel (but it's the same transaction, so no leak)
- Quarkus Messaging connectors
- Quarkus SmallRye Health (same transaction, so no leak)
CVE-2025-49574 has a CVSS score of 6.4 (Medium). The vector is reachable from an adjacent network, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (3.15.6, 3.20.2, 3.24.1); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Remediation advice
After discussion with the Vert.x team, the change will be rolled back in Vert.x 4.x. A new API will be added to Vert.x 5 do distinguish the 2 cases.
Frequently Asked Questions
- What is CVE-2025-49574? CVE-2025-49574 is a medium-severity security vulnerability in io.quarkus:quarkus-vertx (maven), affecting versions <= 3.15.5. It is fixed in 3.15.6, 3.20.2, 3.24.1.
- How severe is CVE-2025-49574? CVE-2025-49574 has a CVSS score of 6.4 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of io.quarkus:quarkus-vertx are affected by CVE-2025-49574? io.quarkus:quarkus-vertx (maven) versions <= 3.15.5 is affected.
- Is there a fix for CVE-2025-49574? Yes. CVE-2025-49574 is fixed in 3.15.6, 3.20.2, 3.24.1. Upgrade to this version or later.
- Is CVE-2025-49574 exploitable, and should I be worried? Whether CVE-2025-49574 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2025-49574 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2025-49574?
- Upgrade
io.quarkus:quarkus-vertxto 3.15.6 or later - Upgrade
io.quarkus:quarkus-vertxto 3.20.2 or later - Upgrade
io.quarkus:quarkus-vertxto 3.24.1 or later
- Upgrade