---
id: "CVE-2026-112269"
kind: "vulnerability"
aliases: ["CVE-2026-112269"]
title: "SGLang: unauthenticated ZMQ registration floods let attackers crash the scheduler"
severity: "high"
cvss: 7.1
epss: null
exploited: false
status: "open"
category: "ai-tooling"
products: []
ecosystems: []
tags: ["ai-tooling", "gpu-clusters", "llm-inference", "mooncake", "self-hosted", "sglang"]
not_affected_if: ["no-mooncake-disaggregation", "socket-not-network-reachable"]
published_at: "2026-10-19T14:17:04+00:00"
first_seen_at: "2026-10-23T21:57:18+00:00"
updated_at: "2026-10-25T03:35:03+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-112269", "first_seen_at": "2026-10-23T21:57:18+00:00"}]
---

# SGLang: unauthenticated ZMQ registration floods let attackers crash the scheduler

SGLang through 0.5.22 with the Mooncake disaggregation backend accepts decode registration messages on the Prefill rank ZMQ PULL socket without authentication. A network-adjacent attacker can send many registrations with unique session IDs and large buffer frames until Prefill memory is exhausted and the scheduler is OOM-killed.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the installed SGLang version with `pip show sglang` and compare it to the fixed release, which the sources do not name.
- Check whether the deployment runs disaggregated prefill/decode with the Mooncake backend (look for `mooncake` in the server launch flags or config).
- Check whether the Prefill ZMQ PULL port is reachable from networks other than the decode nodes, for example with `ss -ltnp` and firewall rules.

## Fix

- Upgrade SGLang past `0.5.22` once a fixed release is available; the sources do not name the fixed version.
- Restrict the Prefill rank's ZMQ port to the decode nodes only with firewall or network policy until patched.
- Unknown whether a configuration option limits registrations; the sources do not say.

## Timeline

- 2026-10-23T21:57:18+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-112269

## From the sources

SGLang through 0.5.22 with the Mooncake disaggregation backend accepts unauthenticated decode registration messages on the Prefill rank ZMQ PULL socket, allowing denial of service. Network-adjacent attackers can send many registrations with unique mooncake_session_id values and large nested-buffer frames to exhaust Prefill memory until the scheduler is OOM-killed.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_