CVE-2026-45536
Netty: Unix-socket fd receive leaks descriptors when peer sends two at once
Description
Netty is a network application framework for development of protocol servers and clients. Prior to versions 4.1.135.Final and 4.2.15.Final, 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). Versions 4.1.135.Final and 4.2.15.Final patch the issue.
How to fix CVE-2026-45536
To remediate CVE-2026-45536, upgrade the affected package to a fixed version below.
- —no fix listed
- —upgrade to 4.2.15.Final or later
- —upgrade to 4.2.15.Final or later
Is CVE-2026-45536 being exploited?
No exploitation signal available. Neither CISA KEV nor a current EPSS score has been published for CVE-2026-45536.
Affected packages (3)
- from 0
- >= 4.2.0.Final, < 4.2.15.Final
- >= 4.2.0.Final, < 4.2.15.Final
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | MEDIUM4.0 | CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L |