🛡️ CVE-2026-6860 — vert.x

🟡 CVSS 5.3 — Medium ✅ No Known Exploit CWE-295 NVD
5.3
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

Vert.x has a DoS via unbounded server-side SNI SslContext cache growth

Potential unbounded server-side SNI SslContext cache growth in Vert.x TLS handling, with = resource-exhaustion / DoS impact. On affected versions, matching server-side SNI names are cached via computeIfAbsent(serverName, ...) in a serverName-keyed SslContext cache.

The implementation differs slightly by branch, but the same sink appears to be present in released versions 4.3.4 through 5.0.11:

  • 4.3.x: SSLHelper
  • 4.4.x / 4.5.x: SslChannelProvider
  • 5.0.x and current master: SslContextProvider

When server-side SNI is enabled and wildcard or otherwise broad hostname mappings are used, an unauthenticated client can send many distinct matching SNI names and cause the server to retain increasing numbers of SslContext entries over time, leading to increasing memory consumption and possible DoS conditions.

Steps to reproduce

1. Configure a Vert.x server with setSsl(true) and setSni(true).

2. Use a keystore or mapping where many distinct SNI names match a wildcard or similarly broad rule.

3. Send repeated connections with distinct matching SNI values.

4. Observe that the SNI cache size grows with the number of unique matching names.

What are the affected versions?

Affected released versions confirmed on origin:

  • 4.3.4 through 4.3.8
  • 4.4.0 through 4.4.9
  • 4.5.0 through 4.5.26
  • 5.0.0 through 5.0.11

Not affected by the same sink:

  • 4.0.x through 4.2.x
  • 4.3.0 through 4.3.3

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity none, availability low.

Weakness class

CVE-2026-6860 is classified as CWE-295: Improper Certificate Validation. A TLS certificate is accepted without proper verification, so a man-in-the-middle can present their own.

Affected software

CVE-2026-6860 is recorded against 3 packages.

  • io.vertx:vertx-core (from 5.0.0 up to 5.0.12)
  • unknown
  • vert.x (from 5.0.0 up to 5.0.11)

Timeline and source

Published on 9 May 2026 and last revised on 2 June 2026. No public exploit is currently recorded for this entry. A vendor advisory or fix has been published. Record sourced from NVD.

References

github.com (Web)
nvd.nist.gov (Advisory)
github.com (Web)
github.com (Package)
github.com (Web)
gitlab.eclipse.org (Web)
vertx.io (Web)
vertx.io (Web)

Details

Severity Medium
CVSS Score 5.3
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
CWE CWE-295
Public Exploit ✅ No
Source NVD
Published 2026-05-09
Updated 2026-08-12
Modified 2026-06-02

Affected Packages

Software From version Fixed in
io.vertx:vertx-core 5.0.0 5.0.12
unknown — —
vert.x 5.0.0 5.0.11

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