GHSA-3g76-f9xq-8vp6
MEDIUMGHSA-3g76-f9xq-8vp6 is a medium-severity (CVSS 5.3) CWE-770 vulnerability in io.vertx:vertx-core. O3 Security confirms whether GHSA-3g76-f9xq-8vp6 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Vert.x has a DoS via unbounded server-side SNI SslContext cache growth
Blast Radius
io.vertx:vertx-core☕io.vertx:vertx-core☕io.vertx:vertx-core☕io.vertx:vertx-coreReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
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:SSLHelper4.4.x/4.5.x:SslChannelProvider5.0.xand currentmaster: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
- Configure a Vert.x server with
setSsl(true)andsetSni(true). - Use a keystore or mapping where many distinct SNI names match a wildcard or similarly broad rule.
- Send repeated connections with distinct matching SNI values.
- 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:
4.3.4through4.3.84.4.0through4.4.94.5.0through4.5.265.0.0through5.0.11
Not affected by the same sink:
4.0.xthrough4.2.x4.3.0through4.3.3
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | io.vertx:vertx-core | ≥ 4.3.4 | No fix |
| ☕Maven | io.vertx:vertx-core | ≥ 4.4.0 | No fix |
| ☕Maven | io.vertx:vertx-core | ≥ 4.5.0&&< 4.5.27 | 4.5.27 |
| ☕Maven | io.vertx:vertx-core | ≥ 5.0.0&&< 5.0.12 | 5.0.12 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for io.vertx:vertx-core. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
No patched version of io.vertx:vertx-core has shipped for GHSA-3g76-f9xq-8vp6 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-3g76-f9xq-8vp6 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-3g76-f9xq-8vp6. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-3g76-f9xq-8vp6 in your dependencies?
O3 detects GHSA-3g76-f9xq-8vp6 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.