# CVE-2026-45536: Netty: Unix-socket fd receive leaks descriptors when peer sends two at once

> A remote attacker can leak file descriptors in Netty applications using Unix sockets, potentially causing resource exhaustion and denial of service.

- **Severity:** Medium 4.0 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 12 Jun 2026
- **Updated:** 12 Jun 2026
- **Also known as:** CLEANSTART-2026-GT99821, CLEANSTART-2026-QW73146, CLEANSTART-2026-TR21269, CLEANSTART-2026-YZ64001, CLEANSTART-2026-ZM65468, DEBIAN-CVE-2026-45536, ECHO-323c-8f17-0fb5, GHSA-w573-9ffj-6ff9, MINI-2mj6-jgrp-42r7, MINI-3h3j-37rw-27q2, MINI-3jv5-fjmj-c8hf, MINI-46p4-ph98-3rqh, MINI-4qm8-h5p4-3jf5, MINI-52v8-xg2r-p4c5, MINI-54rx-wqrx-hm2g, MINI-5gfj-qh7c-h7v4, MINI-5vwv-xqqp-wr4g, MINI-6hwq-wcrx-gq57, MINI-6jqq-c345-cq9q, MINI-6qjg-7f67-fw3w, MINI-6wpp-55qg-526j, MINI-74w7-m879-34f4, MINI-7694-2crm-p2r6, MINI-7ff3-2f98-9q47, MINI-8643-3p6g-2rjc, MINI-8fx7-q2f9-pv6m, MINI-8g42-4w9q-g3g3, MINI-98r2-2q5w-4wgr, MINI-9f7j-2vp5-gq87, MINI-9q6f-gwp7-hrc6, MINI-9vrv-5x2p-vm7p, MINI-c867-wpc3-6474, MINI-cr3r-cf4x-w3r8, MINI-crp2-c964-28j6, MINI-f3pq-95vx-6jpp, MINI-f5wg-5mf2-4vhh, MINI-f9pg-84hv-98m9, MINI-frq4-g9vq-66g4, MINI-fwpx-p9fj-g84w, MINI-g7ch-xrg2-4ffr, MINI-g85q-w5x8-rc42, MINI-g9xh-g6xc-wfgm, MINI-gm69-3qg2-cghj, MINI-gmvp-wh64-75hw, MINI-grfg-6mhc-83xf, MINI-h6rx-6h8x-6pv2, MINI-h83h-8423-qq86, MINI-hjc8-2f75-4r7j, MINI-hw4q-x796-cgcw, MINI-hw9v-rpgf-mx5j, MINI-j7vv-33c9-whjq, MINI-jwm4-8rp9-qvw9, MINI-m229-6w6p-rrgp, MINI-mwmr-7jxc-vrw8, MINI-p2r5-r4w9-5jgw, MINI-ph3v-rg97-6qxg, MINI-pp52-5w28-jm45, MINI-q2hj-g3jr-cv59, MINI-qf58-6hpq-3hhg, MINI-rvmg-9xx9-7q7m, MINI-w5gw-3v69-x887, MINI-xr49-f938-cr5g, MINI-xwvq-76m4-75p6, MINI-xx9h-c97f-3p34, RHLW-2026-778faaa627fd5b22, RHLW-2026-a889d214e9ef7d94, ROOT-APP-MAVEN-CVE-2026-45536, UBUNTU-CVE-2026-45536

## What is CVE-2026-45536?

CVE-2026-45536 is a medium-severity denial of service vulnerability in Netty Netty, published on 12 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official 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.

Weakness: CWE-772 (Missing Release of Resource after Effective Lifetime), CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor)

## Which versions are affected by CVE-2026-45536?

8 open source packages ship an affected version, including io.netty:netty-transport-native-epoll and io.netty:netty-transport-native-kqueue. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `io.netty:netty-transport-native-epoll` | Maven | All versions | 4.1.135.Final |
| `io.netty:netty-transport-native-epoll` | Maven | All versions | 4.1.135.Final |
| `io.netty:netty-transport-native-epoll` | Maven | From 4.2.0.Final | 4.2.15.Final |
| `io.netty:netty-transport-native-epoll` | Maven | From 4.2.0.Final | 4.2.15.Final |
| `io.netty:netty-transport-native-kqueue` | Maven | All versions | 4.1.135.Final |
| `io.netty:netty-transport-native-kqueue` | Maven | All versions | 4.1.135.Final |
| `io.netty:netty-transport-native-kqueue` | Maven | From 4.2.0.Final | 4.2.15.Final |
| `io.netty:netty-transport-native-kqueue` | Maven | From 4.2.0.Final | 4.2.15.Final |

Products: Netty Netty.

## How do I fix CVE-2026-45536?

Upgrade io.netty:netty-transport-native-epoll to a fixed version for your release line: 4.1.135.Final or 4.2.15.Final.

## Is CVE-2026-45536 being exploited?

There is no known exploitation of CVE-2026-45536 in the wild and no public exploit code.

## Other vulnerabilities in Netty Netty

- [CVE-2026-75595](https://insights.sbomify.com/CVE-2026-75595/): Netty: SNI Routing Bypass via Fragmented TLS ClientHello Causing Fallback to Default SslContext (critical 9.1)
- [CVE-2026-75596](https://insights.sbomify.com/CVE-2026-75596/): Netty: Fragmented ClientHello records trigger quadratic pre-handshake reassembly in default SNI parsing (high 8.7)
- [CVE-2026-59901](https://insights.sbomify.com/CVE-2026-59901/): Netty Bzip2Decoder: Infinite Loop in RLE State Machine Leads to Event-Loop Thread Hang (high 8.7)
- [CVE-2026-55851](https://insights.sbomify.com/CVE-2026-55851/): Netty codec-haproxy: Signed-Byte Sentinel Collision in HAProxyMessageDecoder Leads to Unbounded Memory Exhaustion (high 8.7)
- [CVE-2026-56745](https://insights.sbomify.com/CVE-2026-56745/): Netty SpdyHttpDecoder: ByteBuf Reference Leak on RST_STREAM Leads to Native Memory Exhaustion (high 8.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-45536 and fix it if it is affected.

What it is: CVE-2026-45536 is a medium-severity denial of service vulnerability in Netty Netty, published on 12 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-45536 in the wild and no public exploit code.

Affected packages and fixed versions:
- io.netty:netty-transport-native-epoll (Maven): affected all versions; fixed in 4.1.135.Final
- io.netty:netty-transport-native-epoll (Maven): affected all versions; fixed in 4.1.135.Final
- io.netty:netty-transport-native-epoll (Maven): affected from 4.2.0.Final; fixed in 4.2.15.Final
- io.netty:netty-transport-native-epoll (Maven): affected from 4.2.0.Final; fixed in 4.2.15.Final
- io.netty:netty-transport-native-kqueue (Maven): affected all versions; fixed in 4.1.135.Final
- io.netty:netty-transport-native-kqueue (Maven): affected all versions; fixed in 4.1.135.Final
- io.netty:netty-transport-native-kqueue (Maven): affected from 4.2.0.Final; fixed in 4.2.15.Final
- io.netty:netty-transport-native-kqueue (Maven): affected from 4.2.0.Final; fixed in 4.2.15.Final

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-45536/ (Markdown: https://insights.sbomify.com/CVE-2026-45536/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-45536
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-45536
- OSV: https://osv.dev/vulnerability/CVE-2026-45536

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-45536/
Summaries are generated and may contain mistakes; the official description above is the record.