CVE-2026-75595
CRITICALDescription
Netty is an asynchronous, event-driven network application framework. Prior to 4.1.137.Fina and 4.2.17.Final, io.netty.handler.ssl.SslClientHelloHandler#decode checks the wrong offset before reading the four-byte TLS handshake header, so a ClientHello whose handshake header spans records can cause an IndexOutOfBoundsException and invoke select(ctx, null). This selects the default SslContext instead of the SNI-specific context. In deployments where per-SNI clientAuth=REQUIRE is the sole mutual TLS gate, the default SslContext uses clientAuth=NONE or clientAuth=OPTIONAL, and no application-layer certificate verification exists, an unauthenticated remote attacker can bypass the protected route's mutual TLS requirement. This issue is fixed in versions 4.1.137.Final and 4.2.17.Final.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Exploit Intelligence
Low risk: more likely to be exploited than 24% of all known CVEs.
References
Related Vulnerabilities
Other CWE-754 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2024-4367 | High | 8.8 | 71% | - | Fix |
| CVE-2022-39288 | High | 7.5 | 59% | - | Fix |
| CVE-2023-30591 | High | 7.5 | 59% | - | - |
| CVE-2024-3393 | High | 7.5 | 29% | KEV | Fix |
| CVE-2024-43044 | High | 8.8 | 29% | - | Fix |
| CVE-2023-41993 | High | 8.8 | 24% | KEV | Fix |
Common questions
How do I fix CVE-2026-75595?
Upgrade netty to 4.2.17 or later.
Is CVE-2026-75595 being actively exploited?
Not that we know of. CVE-2026-75595 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.32% is the estimated probability that it will be exploited in the next 30 days. That is higher than 24% of all scored CVEs.
How severe is CVE-2026-75595?
CVE-2026-75595 has a CVSS v3 base score of 9.1, rated critical. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2026-75595 affect?
Published advisories record a fix for netty (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
Embed a live status badge for CVE-2026-75595
Markdown
[](https://tridentstack.com/cve/CVE-2026-75595)HTML
<a href="https://tridentstack.com/cve/CVE-2026-75595"><img src="https://tridentstack.com/cve/badge/CVE-2026-75595.svg" alt="CVE-2026-75595"></a>Find and fix vulnerabilities across your fleet
TridentStack Control continuously scans your Windows, macOS, and Linux fleet for known vulnerabilities, prioritizes them by severity and active exploitation, and patches them automatically.
This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-10-26.