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archive/Patch now/AIR-2026-1040
closedclosed 20 Apr 2026Patch now2 Disclosed vulnerabilityAI

CVE-2026-6608: Incorrect control flow vulnerability in LM-Sys FastChat

fastchat

An incorrect control flow vulnerability affects LM-Sys FastChat up to version 0.2.36 in the Arena Side-by-Side View Handler. Remote attackers can exploit the publicly disclosed issue.

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
5.5
EPSS
<0.01 · top 77% · 2026-11-13
EPSS scores by FIRST
fix status
Fix status unknown
first report
20 Apr 2026
last update
20 Apr 2026
CVE ids
CVE-2026-6608other records

Timeline · 1

  1. 20 Apr 2026CVE-2026-6608: A vulnerability was detected in lm-sys fastchat up to 0.2.36.

Sources · 1

Advisories and databases

  1. 2026-04-20
    CVE-2026-6608: A vulnerability was detected in lm-sys fastchat up to 0.2.36.
    NVD · nvd.nist.gov/vuln/detail/CVE-2026-6608

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
control-flow
dates
happened 20 Apr 2026 · first reported 20 Apr 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 10:04Z · updated 2026-10-18 10:04Z

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
# CVE-2026-6608: Incorrect control flow vulnerability in LM-Sys FastChat

https://gcdradar.vercel.app/incidents/cve-2026-6608-incorrect-control-flow-vulnerability-in-lm-sys · AIR-2026-1040 · closed 2026-04-20

- Lane: Patch now
- Severity: 2 (Disclosed vulnerability)
- Fix status: Fix status unknown
- First reported: 2026-04-20
- AI role: Attack on AI
- Products: fastchat
- CVE ids: CVE-2026-6608
- CVSS: 5.5

## Summary

An incorrect control flow vulnerability affects LM-Sys FastChat up to version 0.2.36 in the Arena Side-by-Side View Handler. Remote attackers can exploit the publicly disclosed issue.

## What to do

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

## Latest updates

- 2026-04-20: CVE-2026-6608: A vulnerability was detected in lm-sys fastchat up to 0.2.36. (https://nvd.nist.gov/vuln/detail/CVE-2026-6608)

## Sources

- 2026-04-20 NVD: CVE-2026-6608: A vulnerability was detected in lm-sys fastchat up to 0.2.36. https://nvd.nist.gov/vuln/detail/CVE-2026-6608

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

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