CVE-2026-45536

netty_unix_socket_recvFd sets msg_control to char control[CMSG_SPACE(sizeof(int))] (line 940), 24 bytes on 64-bit Linux. A peer-sent SCM_RIGHTS cmsg carrying two ints has cmsg_len = CMSG_LEN(8) = 24, which fits exactly with no MSG_CTRUNC, so the kernel installs both fds in the receiving process. The subsequent check cmsg->cmsg_len == CMSG_LEN(sizeof(int)) (line 972, expected 20) fails, the branch that would read the fd is skipped, and neither installed fd is closed. The for(;;) loop calls recvmsg again (non-blocking → EAGAIN → Java maps to 0 → read loop exits normally), leaving two leaked fds per message. There is no MSG_CTRUNC handling. Reachable via Epoll/KQueue DomainSocketChannel when the application opts into DomainSocketReadMode.FILE_DESCRIPTORS (non-default).

CVE-2026-45536 has a CVSS score of 4.0 (Medium). The vector is requires local access, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (4.2.15.Final, 4.1.135.Final); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-45536? CVE-2026-45536 is a medium-severity security vulnerability in io.netty:netty-transport-native-epoll (maven), affecting versions >= 4.2.0.Final, <= 4.2.14.Final. It is fixed in 4.2.15.Final, 4.1.135.Final.
2. How severe is CVE-2026-45536? CVE-2026-45536 has a CVSS score of 4.0 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which packages are affected by CVE-2026-45536?
   • io.netty:netty-transport-native-epoll (maven) (versions >= 4.2.0.Final, <= 4.2.14.Final)
   • io.netty:netty-transport-native-kqueue (maven) (versions >= 4.2.0.Final, <= 4.2.14.Final)
4. Is there a fix for CVE-2026-45536? Yes. CVE-2026-45536 is fixed in 4.2.15.Final, 4.1.135.Final. Upgrade to this version or later.
5. Is CVE-2026-45536 exploitable, and should I be worried? Whether CVE-2026-45536 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-45536 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-45536?
   • Upgrade io.netty:netty-transport-native-epoll to 4.2.15.Final or later
   • Upgrade io.netty:netty-transport-native-kqueue to 4.2.15.Final or later
   • Upgrade io.netty:netty-transport-native-kqueue to 4.1.135.Final or later
   • Upgrade io.netty:netty-transport-native-epoll to 4.1.135.Final or later