# CVE-2026-103223: Eclipse Vert.x PostgreSQL client unbounded memory allocation

Source: https://junglewise.ai/threats/cve-2026-103223-in-eclipse-vert-x-versions-4-0-0-4-5-34-or-5-0-0-5-0-12-or-5-1-0  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-15. Updated: 2026-10-20  
License: CC BY 4.0 with a link back

CVE-2026-103223 · Severity: medium · CVSS 5.9 · Published 2026-10-15

The Vert.x PostgreSQL client, a Java library for connecting applications to PostgreSQL databases, is vulnerable to denial of service when connecting to a malicious or compromised PostgreSQL server. An attacker can send a specially crafted message that causes the client to allocate unbounded memory, exhausting system resources and crashing the application before it even completes authentication.

Technologies: [Eclipse Vert.X](https://junglewise.ai/threats/technologies/eclipse-vert-x). Vendors: [Eclipse](https://junglewise.ai/threats/vendors/eclipse).

## Quick answers

**Is CVE-2026-103223 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-103223 being exploited in the wild.

**How severe is CVE-2026-103223?** Medium severity, with a CVSS score of 5.9, published 15 October 2026.

**Which products and versions are affected?** Eclipse Vertx-Pg-Client 4.0.0–4.5.34, 5.0.0–5.0.12, 5.1.0–5.1.9, 5.2.0.

**Is there a fix for CVE-2026-103223?** Yes: fixed in vertx-pg-client 4.5.35, 5.1.10, 5.2.1. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-103223 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-103223?** Check whether you run Eclipse Vert.X or Eclipse Vertx-Pg-Client 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.

## How to fix

- Fixed in vertx-pg-client 4.5.35, 5.1.10, 5.2.1

## Technical details

The PostgreSQL wire protocol message decoder in vertx-pg-client fails to validate the maximum value of the 4-byte message length field, allowing a network attacker to specify arbitrarily large lengths (up to Integer.MAX_VALUE). The decoder then accumulates TCP data into a composite buffer without bounds, exhausting heap memory. This occurs before client authentication completes, requiring only network access to a PostgreSQL server endpoint.

## Affected products

- Eclipse vertx-pg-client 4.0.0–4.5.34, 5.0.0–5.0.12, 5.1.0–5.1.9, 5.2.0

## Timeline

- 2026-10-15: disclosed
- 2026-10-07: advisory: GitHub Security Advisory published

## References

- [https://github.com/eclipse-vertx/vertx-sql-client/security/advisories/GHSA-hm2j-xp3c-jff2](https://github.com/eclipse-vertx/vertx-sql-client/security/advisories/GHSA-hm2j-xp3c-jff2)
- [https://gitlab.eclipse.org/security/cve-assignment/-/work_items/354](https://gitlab.eclipse.org/security/cve-assignment/-/work_items/354)

## Related threats

- [Eclipse Vert.x STOMP FrameParser heap exhaustion](https://junglewise.ai/threats/cve-2026-118487-in-eclipse-vert-x-versions-4-0-0-4-5-35-or-5-0-0-5-2-2-the)
- [Eclipse Vert.x CachingWebClient cross-user cache disclosure](https://junglewise.ai/threats/cve-2026-118489-in-eclipse-vert-x-versions-4-0-0-4-5-35-or-5-0-0-5-2-2-when-one)
- [Eclipse Vert.x gRPC compression bomb denial of service](https://junglewise.ai/threats/cve-2026-102477-in-eclipse-vert-x-versions-4-0-0-4-5-34-or-5-0-0-5-0-12-or-5-1-0)
- [Eclipse Vert.x DB2 client unsafe Java deserialization in UDT handling](https://junglewise.ai/threats/cve-2026-102469-in-eclipse-vert-x-versions-4-0-0-4-5-34-or-5-0-0-5-0-12-or-5-1-0)
- [Eclipse Vert.x MySQL client denial of service via uncapped column count](https://junglewise.ai/threats/cve-2026-102466-in-eclipse-vert-x-versions-4-0-0-4-5-34-or-5-0-0-5-0-12-or-5-1-0)