CVE-2026-93838 SGLang through 0.5.20 Unbounded Memory Allocation via STAGING_REQ chunk_idx
Attackers with internal ZMQ access can cause denial of service in SGLang by sending large chunk indices, exhausting memory in disaggregated deployments.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-93838?
CVE-2026-93838 is a high-severity denial of service vulnerability in sgl-project sglang, published on 18 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-770
Which versions are affected by CVE-2026-93838?
How do I fix CVE-2026-93838?
Upgrade to a fixed version.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-93838 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-93838 exists.
Sources
Also known as GHSA-2wcg-j54r-m6wm.