Vulnerability in Io.netty Netty-Codec-Redis

CVE-2026-42586

Netty is an asynchronous, event-driven network application framework. Prior to 4.2.13.Final and 4.1.133.Final, the Netty Redis codec encoder (RedisEncoder) writes user-controlled string content directly to the network output buffer without validating or sanitizing CRLF (\r\n) characters. Since the Redis Serialization Protocol (RESP) uses CRLF as the command/response delimiter, an attacker who can control the content of a Redis message can inject arbitrary Redis commands or forge fake responses. This vulnerability is fixed in 4.2.13.Final and 4.1.133.Final.

Vulnerability class: CRLF Injection

Published · last modified .

CVSS v3 metric

CVSS v3 base score 6.8 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N.

EPSS exploit prediction

EPSS: 0.002 (6.8th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 7th percentile — 6.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-42586: held from 0.002 to 0.002.

EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: -0.000

Affected products

  • Io.netty Netty-Codec-Redis — versions >= 4.2.0.Alpha1, < 4.2.13.Final, < 4.1.133.Final
  • Netty — versions >= 4.2.0.Alpha1, < 4.2.13.Final, < 4.1.133.Final

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-42586?
CVE-2026-42586 is a medium-severity vulnerability in Io.netty Netty-Codec-Redis, classified under CRLF Injection. CVSS score: 6.8/10. Published 2026-05-13.
How severe is CVE-2026-42586?
Medium severity. CVSS v3 base score is 6.8 out of 10.