Netty has an IPv6 Subnet Filter Bypass via Incorrect Comparator Masking
CVE-2026-44249

8.1HIGH

Key Information:

Vendor

Netty

Status
Netty
Vendor
CVE Published:
11 June 2026

What is CVE-2026-44249?

Netty is a network application framework for development of protocol servers and clients. In netty-handler prior to versions 4.1.135.Final and 4.2.15.Final, an attacker can bypass IPv6 subnet rules due to an incorrect masking operation in IpSubnetFilterRule.compareTo(). Valid public IP addresses can bypass the restrictions. Versions 4.1.135.Final and 4.2.15.Final patch the issue.

Affected Version(s)

netty >= 4.2.0.Final, < 4.2.15.Final < 4.2.0.Final, 4.2.15.Final

netty < 4.1.135.Final < 4.1.135.Final

References

https://github.com/netty/netty/security/advisories/GHSA-3...
x_refsource_CONFIRM
https://github.com/netty/netty/releases/tag/netty-4.1.135...
x_refsource_MISC
https://github.com/netty/netty/releases/tag/netty-4.2.15....
x_refsource_MISC

CVSS V3.1

Score:
8.1
Severity:
HIGH
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
High
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.