CVE-2026-44248Netty is an asynchronous, event-driven network application framework.
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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
- 7.5 HIGH (v3.1, NVD)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Weakness (CWE)
- CWE-400, CWE-770
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Not given
- NVD analysis
- Modified
- Record last updated
- Sep 11, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
netty netty netty:netty | before 4.1.133; from 4.2.0 before 4.2.13 | NVD |
References
- https://github.com/netty/netty/security/advisories/GHSA-jfg9-48mv-9qgxvendor-advisory
- 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
- https://access.redhat.com/security/cve/CVE-2026-44248
- https://bugzilla.redhat.com/show_bug.cgi?id=2477231
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-44248.json
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.