{"cve":"CVE-2026-44248","nvd":{"published":"2026-05-13T19:17:27.143","modified":"2026-10-26T17:10:03.270","status":"Modified","description":"Netty is an asynchronous, event-driven network application framework. Prior to 4.2.13.Final and 4.1.133.Final, the MQTT 5 header Properties section is parsed and buffered before any message size limit is applied. Specifically, in MqttDecoder, the decodeVariableHeader() method is called before the bytesRemainingBeforeVariableHeader > maxBytesInMessage check. The decodeVariableHeader() can call other methods which will call decodeProperties(). Effectively, Netty does not apply any limits to the size of the properties being decoded. Additionally, because MqttDecoder extends ReplayingDecoder, Netty will repeatedly re-parse the enormous Properties sections and buffer the bytes in memory, until the entire thing parses to completion. This can cause high resource usage in both CPU and memory. This vulnerability is fixed in 4.2.13.Final and 4.1.133.Final.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5},"cwes":["CWE-400","CWE-770"],"references":["https://github.com/netty/netty/security/advisories/GHSA-jfg9-48mv-9qgx","https://access.redhat.com/errata/RHSA-2026:37390","https://access.redhat.com/errata/RHSA-2026:41951","https://access.redhat.com/errata/RHSA-2026:66488","https://access.redhat.com/errata/RHSA-2026:66545"],"products":["netty:netty"],"source":"nvd","synced_at":"2026-10-26T17:39:09.812804557+00:00"},"epss":{"cve":"CVE-2026-44248","score":0.00563,"percentile":0.46569,"date":"2026-10-26"},"kev":null,"osv":[{"id":"GHSA-jfg9-48mv-9qgx","url":"https://osv.dev/vulnerability/GHSA-jfg9-48mv-9qgx","summary":"Netty MQTT: Resource exhaustion in MqttDecoder","modified":"2026-09-10T03:51:06.220307671Z","packages":[{"ecosystem":"Maven","name":"io.netty:netty-codec-mqtt","purl":"pkg:maven/io.netty/netty-codec-mqtt","ranges":[">=4.2.0.Alpha1 <4.2.13.Final"],"fixed":["4.2.13.Final"]},{"ecosystem":"Maven","name":"io.netty:netty-codec-mqtt","purl":"pkg:maven/io.netty/netty-codec-mqtt","ranges":["<4.1.133.Final"],"fixed":["4.1.133.Final"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}