CVE-2026-103223 Denial of service in Eclipse Vert.x

High 8.2 Published 15 Oct 2026 Updated 15 Oct 2026

A malicious PostgreSQL server can cause an out-of-memory crash in Eclipse Vert.x clients by sending oversized message length headers.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2026-103223?

CVE-2026-103223 is a high-severity denial of service vulnerability in Eclipse Vert.x, published on 15 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

In Eclipse Vert.x versions [4.0.0, 4.5.34] or [5.0.0,5.0.12] or [5.1.0,5.1.9] or [5.2.0, 5.2.0], the PostgreSQL message decoder reads the 4-byte message length field from the PostgreSQL wire protocol without any maximum validation. A malicious, compromised, or man-in-the-middle PostgreSQL server can send a message header with the length field set to an extremely large value (up to Integer.MAX_VALUE), causing the decoder to accumulate subsequent TCP data into a composite buffer without bound, leading to unbounded memory allocation on the client and an out-of-memory crash. This occurs before authentication completes.

The impacted component is io.vertx:vertx-pg-client.

Weakness: CWE-789

Which versions are affected by CVE-2026-103223?

It affects 1 product.

Products include Eclipse Vert.x.

How do I fix CVE-2026-103223?

No fix has been published for CVE-2026-103223 yet. Limit exposure of the affected software until one is available.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2026-103223 being exploited?

There is no known exploitation of CVE-2026-103223 in the wild and no public exploit code.

Sources

Also known as GHSA-h6w8-ffgq-ghpg, GHSA-hm2j-xp3c-jff2.