CVE-2026-93838 Details
Description
SGLang versions through 0.5.20 contain an unbounded memory allocation vulnerability in handle_staging_req() that fails to validate chunk_idx from ZMQ STAGING_REQ frames in prefill/decode disaggregation deployments. Attackers with access to the decode engine's internal ZMQ rank port can send a frame with an extremely large chunk_idx value, causing the scheduler to allocate memory until the system runs out and terminates the process.
A vulnerability exists in SGLang versions through 0.5.20, allowing for unbounded memory allocation. This issue arises in the 'handle_staging_req()' function, where the 'chunk_idx' from ZMQ STAGING_REQ frames is not properly validated. Attackers with access to the decode engine's internal ZMQ rank port can exploit this by sending a frame with a large 'chunk_idx' value. This leads to excessive memory allocation, causing the system to run out of resources and terminate the process. The vulnerability is particularly pronounced in prefill/decode disaggregation deployments, where the Decode scheduler can be overwhelmed, causing a denial-of-service condition.
Users can upgrade to SGLang version 0.5.21 or later, where this vulnerability has been addressed.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Sep 18, 2026CISA-ADP
Assessed Sep 18, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/sgl-project/sglang/issues/39764 | CISA-ADP | ExploitIssue TrackingTechnical DescriptionVendor |
| https://github.com/sgl-project/sglang | [email protected] | Vendor |
| https://github.com/sgl-project/sglang/blob/v0.5.20/python/sglang/srt/disaggregation/common/conn.py#L1636-L1640 | [email protected] | Source CodeVendor |
| https://github.com/sgl-project/sglang/blob/v0.5.20/python/sglang/srt/disaggregation/common/staging_handler.py#L781 | [email protected] | Source CodeVendor |
| https://github.com/sgl-project/sglang/blob/v0.5.20/python/sglang/srt/disaggregation/common/staging_handler.py#L848-L860 | [email protected] | Source CodeVendor |
| https://github.com/sgl-project/sglang/issues/39764 | [email protected] | ExploitIssue TrackingTechnical DescriptionVendor |
| https://www.vulncheck.com/advisories/sglang-through-0.5.20-unbounded-memory-allocation-via-staging-req-chunk-idx | [email protected] | AdvisoryBundleVendor |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-770 | Allocation of Resources Without Limits or Throttling | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| SGLang | <= 0.5.20 (semver) |
CPE
Remediation
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Change History
2 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Sep 18, 2026 | CVE Modified | CISA-ADP |
| Sep 18, 2026 | New CVE Received | [email protected] |