GHSA-w573-9ffj-6ff9

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GHSA-w573-9ffj-6ff9

Summary: Netty: Unix-socket fd receive leaks descriptors when peer sends two at once

Details: 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).

References: https://github.com/netty/netty/security/advisories/GHSA-w573-9ffj-6ff9, https://nvd.nist.gov/vuln/detail/CVE-2026-45536, https://github.com/netty/netty, https://github.com/netty/netty/releases/tag/netty-4.1.135.Final, https://github.com/netty/netty/releases/tag/netty-4.2.15.Final