Widely used Netty framework; IPv6 subnet bypass could expose services across many apps.
CVE-2026-44249
Netty IPv6 subnet bypass via IpSubnetFilterRule masking.
Is CVE-2026-44249 being exploited?
Not confirmed. CVE-2026-44249 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 1.0% probability of exploitation in the next 30 days.
How severe is CVE-2026-44249?
CVE-2026-44249 is rated High with a CVSS score of 8.1. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-44249?
Yes. A fix has been recorded for CVE-2026-44249. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-44249 affect?
CVE-2026-44249 affects Netty netty-handler < 4.1.135.Final, Netty netty-handler < 4.2.15.Final. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-44249?
Upgrade to 4.1.135.Final or 4.2.15.Final
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Bypass IPv6 subnet restrictions on Netty-based services, enabling unauthorized network access.
Immediate action required
- affected>= 4.2.0.Final and < 4.2.15.Final
- affected< 4.1.135.Final
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.