# CVE-2026-6860: Eclipse Vert.x DoS via unbounded SNI SslContext cache growth

Source: https://junglewise.ai/threats/cve-2026-6860-eclipse-vert-x-dos-via-unbounded-sni-sslcontext-cache-growth  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-06. Updated: 2026-06-02  
License: CC BY 4.0 with a link back

CVE-2026-6860 · Severity: medium · CVSS 5.3 · Published 2026-05-06

Eclipse Vert.x, a toolkit for building reactive applications on the JVM, is vulnerable to a denial-of-service attack. An unauthenticated attacker can send a large number of specially crafted connection requests that cause the server to consume excessive memory. This can eventually lead to the application crashing or becoming unresponsive, disrupting business operations.

Technologies: [io.vertx:vertx-core (Maven)](https://junglewise.ai/threats/technologies/io-vertx-vertx-core). Vendors: [Eclipse Foundation](https://junglewise.ai/threats/vendors/eclipse-foundation), [Maven](https://junglewise.ai/threats/vendors/maven).

## Quick answers

**Is CVE-2026-6860 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-6860 being exploited in the wild.

**How severe is CVE-2026-6860?** Medium severity, with a CVSS score of 5.3, published 6 May 2026.

**Which products and versions are affected?** Eclipse Foundation Vert.x 4.3.4 - 4.3.8, 4.4.0 - 4.4.9, 4.5.0 - 4.5.25, 5.0.0 - 5.0.8, 4.3.4 - 4.3.8, 4.4.0 - 4.4.9, 4.5.0 - 4.5.26, 5.0.0 - 5.0.11; io.vertx:vertx-core (Maven) ECOSYSTEM:introduced=4.3.4,last_affected=4.3.8.

**Is there a fix for CVE-2026-6860?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-6860 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-6860?** Check whether you run Eclipse Foundation Vert.x or io.vertx:vertx-core (Maven) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A resource exhaustion vulnerability exists in Vert.x TLS handling when server-side SNI is enabled with broad or wildcard hostname mappings. The vulnerability is caused by the use of `computeIfAbsent` in a cache keyed by the SNI server name, which allows an unauthenticated remote attacker to trigger unbounded cache growth by sending many distinct matching SNI names. This leads to excessive memory consumption and a potential Denial of Service (DoS). The issue affects multiple components across different versions, including SSLHelper, SslChannelProvider, and SslContextProvider. Patches are available in versions 4.5.27 and 5.0.12.

## Affected products

- Eclipse Vert.x 4.3.4 - 4.3.8, 4.4.0 - 4.4.9, 4.5.0 - 4.5.26, 5.0.0 - 5.0.11

## Identifiers

- CVE-2026-6860
- GHSA-3g76-f9xq-8vp6

## Timeline

- 2026-05-06: disclosed
- 2026-05-09: advisory

## References

- [https://api.github.com/users/shblue21](https://api.github.com/users/shblue21)
- [https://github.com/shblue21](https://github.com/shblue21)
- [https://api.github.com/users/shblue21/gists%7B/gist_id%7D](https://api.github.com/users/shblue21/gists%7B/gist_id%7D)
- [https://api.github.com/users/shblue21/repos](https://api.github.com/users/shblue21/repos)
- [https://avatars.githubusercontent.com/u/25363091?v=4](https://avatars.githubusercontent.com/u/25363091?v=4)
- [https://api.github.com/users/shblue21/events%7B/privacy%7D](https://api.github.com/users/shblue21/events%7B/privacy%7D)

## Related threats

- [Eclipse Vert.x sensitive header propagation in HttpClient redirect handler](https://junglewise.ai/threats/cve-2026-15075-eclipse-vert-x-sensitive-header-propagation-in-httpclient)
- [Vert.x Web static handler component cache can be manipulated to deny the access to static files](https://junglewise.ai/threats/cve-2026-1002-vert-x-web-static-handler-component-cache-can-be-manipulated-to)
- [Eclipse Vert.x vulnerable to a memory leak in TCP servers](https://junglewise.ai/threats/cve-2024-1300-eclipse-vert-x-vulnerable-to-a-memory-leak-in-tcp-servers)
- [Eclipse Vert.x memory leak](https://junglewise.ai/threats/cve-2024-1023-eclipse-vert-x-memory-leak)
- [Moderate severity vulnerability that affects io.vertx:vertx-core](https://junglewise.ai/threats/cve-2018-12537-moderate-severity-vulnerability-that-affects-io-vertx-vertx-core)