gcdRadar
archive/Patch now/AIR-2026-0152
closedclosed 19 Sep 2026Patch now2 Disclosed vulnerabilityAI

vLLM bad_words token index validation flaw in SamplingParams

vLLM

A vulnerability in vLLM allows attackers to supply out-of-bounds token indices that corrupt logits memory of concurrent requests. This causes different in-flight HTTP requests to return incorrect tokens.

disclosed CVENo confirmed exploitation, so this record is tracked as a disclosed vulnerability and not counted as an incident. It moves into the counts if CISA or the vendor confirms exploitation. Why

CVSS
3.1
EPSS
<0.01 · top 90% · 2026-11-13
EPSS scores by FIRST
fix status
Fix status unknown
first report
19 Sep 2026
last update
19 Sep 2026
CVE ids
CVE-2026-93989other records

Timeline · 1

  1. 19 Sep 2026CVE-2026-93989: vLLM through 0.29.0 fails to properly validate bad_words token indices against the model's generation output width in…

Sources · 1

Advisories and databases

  1. 2026-09-19
    CVE-2026-93989: vLLM through 0.29.0 fails to properly validate bad_words token indices against the model's generation output width in…
    NVD · nvd.nist.gov/vuln/detail/CVE-2026-93989

Titles and links belong to their publishers. The summary above is written by gcdRadar in its own words; data is CC BY-SA 4.0.

Classification

lane
Patch now
AI role
Attack on AI
categories
Infrastructure vulnerability
severity
2 · Disclosed vulnerability
fix status
Fix status unknown
targets
Framework / tooling
owasp llm top 10
LLM03:2025 Supply Chain
mitre atlas
no technique for these categories
tags
vllm
dates
happened 19 Sep 2026 · first reported 19 Sep 2026
origin
NVD
Vulnerability record from NVD / the GitHub Advisory Database. This product uses the NVD API but is not endorsed or certified by the NVD.
record
confidence 0.95 · created 2026-10-18 06:33Z · updated 2026-10-18 06:33Z

Lane, AI role, categories and severity come from the classifier; the OWASP and ATLAS rows are derived from the categories. How these are assigned

Copy a brief

This record as a short Markdown brief, for a ticket, a chat or a coding agent.

the brief as text
# vLLM bad_words token index validation flaw in SamplingParams

https://gcdradar.vercel.app/incidents/vllm-bad-words-token-index-validation-flaw-in-samplingparams · AIR-2026-0152 · closed 2026-09-19

- Lane: Patch now
- Severity: 2 (Disclosed vulnerability)
- Fix status: Fix status unknown
- First reported: 2026-09-19
- AI role: Attack on AI
- Products: vLLM
- CVE ids: CVE-2026-93989
- CVSS: 3.1

## Summary

A vulnerability in vLLM allows attackers to supply out-of-bounds token indices that corrupt logits memory of concurrent requests. This causes different in-flight HTTP requests to return incorrect tokens.

## What to do

No action recorded; read the sources below and the vendor's advisory.

## Latest updates

- 2026-09-19: CVE-2026-93989: vLLM through 0.29.0 fails to properly validate bad_words token indices against the model's generation output width in… (https://nvd.nist.gov/vuln/detail/CVE-2026-93989)

## Sources

- 2026-09-19 NVD: CVE-2026-93989: vLLM through 0.29.0 fails to properly validate bad_words token indices against the model's generation output width in… https://nvd.nist.gov/vuln/detail/CVE-2026-93989

Verify against the vendor's advisory before changing production. Data CC BY-SA 4.0, https://gcdradar.vercel.app.

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