Bug 2538642 (CVE-2026-93840)

Summary: CVE-2026-93840 vllm: vLLM: Information disclosure via incorrect token ID validation
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: alinfoot, bbrownin, dtrifiro, weaton
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in vLLM. This vulnerability arises from incorrect validation of `allowed_token_ids` against the tokenizer length instead of the model's output logits width. A remote attacker can exploit this by supplying token IDs that exceed the output vocabulary, which bypasses validation. This can lead to the corruption of the GPU logits state, potentially allowing concurrent requests to sample tokens outside their intended allowlists, resulting in information disclosure.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-09-22 19:49:30 UTC 
vLLM before 0.29.0 validates allowed_token_ids against tokenizer length instead of model output logits width in SamplingParams._validate_allowed_token_ids(). Attackers can supply token IDs above the output vocabulary that pass validation, causing LogitBiasState to corrupt GPU logits state and allow concurrent requests to sample tokens outside their allowlists.