# CVE-2026-94570: SGLang Decode worker DoS in ZeroMQ control message handling

Source: https://junglewise.ai/threats/cve-2026-94570-sglang-contains-a-dos-vulnerability-caused-by-missing-input  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-22. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-94570 · Severity: medium · CVSS 5.9 · Published 2026-09-22

SGLang is a framework for serving large language models. When deployed with disaggregated Prefill and Decode workers using the Mooncake transfer backend, an attacker with network access to the internal Decode control socket can send malformed messages that crash the control thread, preventing inference requests from completing. The HTTP health endpoint remains responsive, masking the failure from monitoring systems.

Technologies: [SGLang](https://junglewise.ai/threats/technologies/sglang-sglang). Vendors: [SGLang](https://junglewise.ai/threats/vendors/sglang).

## Quick answers

**Is CVE-2026-94570 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-94570 being exploited in the wild.

**How severe is CVE-2026-94570?** Medium severity, with a CVSS score of 5.9, published 22 September 2026.

**Which products and versions are affected?** SGLang 0.5.15.post1 and possibly other versions with Mooncake disaggregation.

**Is there a fix for CVE-2026-94570?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-94570 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-94570?** Check whether you run SGLang at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

Missing bounds validation on the buffer_index parameter in AUX_DATA ZeroMQ multipart messages allows an unauthenticated network peer to trigger an uncaught IndexError in the Decode worker's control-receive thread. The vulnerability is triggered when AuxDataCodec.deserialize_data_to_buffer() accesses kv_args.aux_data_ptrs with an out-of-range index, terminating the long-lived thread without recovery. Exploitation requires network reachability to the Decode worker's dynamically allocated ZeroMQ control PULL socket and is present in SGLang 0.5.15.post1 with Mooncake disaggregation enabled.

## Affected products

- SGLang SGLang 0.5.15.post1 and possibly other versions with Mooncake disaggregation

## Timeline

- 2026-09-22: disclosed

## References

- [https://gist.github.com/yyymk/b5892625cb5efa2bffd36e0b05334ae8](https://gist.github.com/yyymk/b5892625cb5efa2bffd36e0b05334ae8)

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