Resource exhaustion in Io.netty Netty-Codec
CVE-2026-42583
Netty is an asynchronous, event-driven network application framework. Prior to 4.2.13.Final and 4.1.133.Final, Lz4FrameDecoder allocates a ByteBuf of size decompressedLength (up to 32 MB per block) before LZ4 runs. A peer only needs a 21-byte header plus compressedLength payload bytes - 22 bytes if compressedLength == 1 - to force that allocation. This vulnerability is fixed in 4.2.13.Final and 4.1.133.Final.
Vulnerability class: DoS (Denial of Service)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.005 (39.4th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 39th percentile — 39.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: +0.000
Affected products
- Io.netty Netty-Codec — versions < 4.1.133.Final
- Io.netty Netty-Codec-Compression — versions < 4.2.13.Final
- Netty — versions >= 4.2.0.Alpha1, < 4.2.13.Final, < 4.1.133.Final
Weakness classification (CWE)
References
- github.com/netty/netty/security/advisories/GHSA-mj4r-2hfc-f8p6 (Exploit, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-42583?
- CVE-2026-42583 is a high-severity vulnerability in Io.netty Netty-Codec, classified under Uncontrolled Resource Consumption. CVSS score: 7.5/10. Published 2026-05-13.
- How severe is CVE-2026-42583?
- High severity. CVSS v3 base score is 7.5 out of 10.