CVE-2026-102464
A malicious or compromised MQTT broker can exploit this by sending QoS 2 PUBLISH messages with distinct packet identifiers and withholding the PUBREL responses.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.31%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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 Eclipse Vert.x MQTT (vertx-mqtt) MqttClient stores every inbound QoS 2 PUBLISH message received from the broker in an internal map (qos2inbound) while awaiting the corresponding PUBREL packet to complete the QoS 2 handshake. This map has no size limit; the maxInflightQueue option is enforced only on the outbound publish path and does not constrain inbound message retention. A malicious or compromised MQTT broker can exploit this by sending QoS 2 PUBLISH messages with distinct packet identifiers and withholding the PUBREL responses. Each incomplete handshake causes the client to retain the full publish message (topic, payload, and metadata) indefinitely, leading to unbounded memory growth in the Vert.x process. This can degrade the MQTT-consuming application or cause out-of-memory termination. The impacted component is io.vertx:vertx-mqtt.
- CVSS 4.0
- 8.2 HIGHCVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
- EPSS
- 0.31% probability · 23th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-770
- Affected
- eclipse/vert.x
- Source
- emo@eclipse.org
EPSS moved from 0.3% on 15 October 2026 to 0.3% on 26 October 2026.
References
- https://github.com/vert-x3/vertx-mqtt/security/advisories/GHSA-46xj-5735-6qrpVendor Advisory
- https://gitlab.eclipse.org/security/cve-assignment/-/work_items/344Issue Tracking, Third Party Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.