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.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Attack Requirements
Present
Additional conditions required
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
None
No data leak
Integrity
None
No data modification
Availability
High
Complete denial of service
CVSS Vector v4.0
Weakness Type (CWE)
Vulnerable Products 1
| Configuration | From (including) | Up to (excluding) |
|---|---|---|
|
Lmsys Sglang
cpe:2.3:a:lmsys:sglang:*:*:*:*:*:*:*:*
|
— |
<= 0.5.20
|
References 6
https://github.com/sgl-project/sglang
disclosure@vulncheck.com
https://github.com/sgl-project/sglang/blob/v0.5.20/python/sglang/srt/disaggrega…
disclosure@vulncheck.com
https://github.com/sgl-project/sglang/blob/v0.5.20/python/sglang/srt/disaggrega…
disclosure@vulncheck.com
https://github.com/sgl-project/sglang/blob/v0.5.20/python/sglang/srt/disaggrega…
disclosure@vulncheck.com
https://github.com/sgl-project/sglang/issues/39764
disclosure@vulncheck.com
https://www.vulncheck.com/advisories/sglang-through-0.5.20-unbounded-memory-all…
disclosure@vulncheck.com