Description
SGLang through 0.5.19 in prefill/decode disaggregation mode with Mooncake KV transfer backend fails to validate bootstrap_room values, allowing unbounded transfer state allocation. Unauthenticated attackers can reach the decode engine's POST /generate endpoint and submit arbitrary bootstrap_room values to exhaust prefill process memory until out-of-memory termination.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| sgl-project | sglang | ≤ 0.5.19 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | python-sglang | 0.5.20-1.1 | openSUSE-SU-2026:11865-1 |
Advisories 1
- openSUSE-SU-2026:11865-1 python313-sglang-0.5.20-1.1 on GA media SUSE / openSUSE Security Updates · Sep 24, 2026
References
- GitHub Issue #39428 issue-tracking
- https://github.com/sgl-project/sglang product
- https://github.com/sgl-project/sglang/blob/v0.5.19/python/sglang/srt/disaggregation/mooncake/conn.py#L2118-L2119 technical-description
- https://github.com/sgl-project/sglang/blob/v0.5.19/python/sglang/srt/disaggregation/mooncake/conn.py#L1988-L1990 technical-description
- https://github.com/sgl-project/sglang/blob/v0.5.19/python/sglang/srt/managers/io_struct.py#L281 technical-description
- https://github.com/sgl-project/sglang/blob/v0.5.19/python/sglang/srt/managers/scheduler.py#L2672-L2690 technical-description
- VulnCheck Advisory: SGLang through 0.5.19 Unbounded Memory Allocation via bootstrap_room third-party-advisory