CVE-2026-42586: netty — Exploit & Fix

Description

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.

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CVSS v3.1 Score

6.8

MEDIUM

CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N

EPSS — Exploit Prediction

0.0001

Probability of exploitation

0.01%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-93 CWE-93

Affected Products

Vendor	Product	Versions
netty	netty	< 4.1.133
netty	netty	4.2.0 — 4.2.13

References

Advisories & Patches

https://github.com/netty/netty/security/advisories/GHSA-rgrr-p7gp-5xj7 https://github.com/netty/netty/security/advisories/GHSA-rgrr-p7gp-5xj7

Exploits

https://github.com/netty/netty/security/advisories/GHSA-rgrr-p7gp-5xj7 https://github.com/netty/netty/security/advisories/GHSA-rgrr-p7gp-5xj7

Frequently Asked Questions

What is 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. It has a CVSS v3.1 base score of 6.8 (MEDIUM).

How severe is CVE-2026-42586? +

CVE-2026-42586 has a CVSS v3.1 score of 6.8 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0001, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-42586? +

CVE-2026-42586 affects products from netty, specifically: netty. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-42586? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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