CVE-2026-6608 | lm-sys fastchat up to 0.2.36 Arena Side-by-Side View add_text control flow (Issue 3834)

VDB-358243 · SUBMIT #792228 · CVE-2026-6608 LM-SYS FASTCHAT UP TO 0.2.36 ARENA SIDE-BY-SIDE VIEW ADD_TEXT CONTROL FLOW HISTORYDIFFRELATEJSONXMLCTI CVSS Meta Temp Score Current Exploit Price (≈) CTI Interest Score 4.8 $0-$5k 2.04 Summaryinfo A vulnerability marked as problematic has been reported in lm-sys fastchat up to 0.2.36. The affected element is the function add_text of the component Arena Side-by-Side View Handler. This manipulation causes control flow. This vulnerability appears as CVE-2026-6608. The attack may be initiated remotely. In addition, an exploit is available. The root cause was fixed in commit 34eca62 for gradio_block_arena_named.py, but three other files were missed. Detailsinfo A vulnerability was found in lm-sys fastchat up to 0.2.36. It has been declared as problematic. Affected by this vulnerability is the function add_text of the component Arena Side-by-Side View Handler. The manipulation with an unknown input leads to a control flow vulnerability. The CWE definition for the vulnerability is CWE-670. The code contains a control flow path that does not reflect the algorithm that the path is intended to implement, leading to incorrect behavior any time this path is navigated. As an impact it is known to affect integrity. It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-6608. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details and also a public exploit are known. It is possible to download the exploit at gist.github.com. It is declared as proof-of-concept. The root cause was fixed in commit 34eca62 for gradio_block_arena_named.py, but three other files were missed. There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product. Productinfo Type Chat Software Vendor lm-sys Name fastchat Version 0.2.0 0.2.1 0.2.2 0.2.3 0.2.4 0.2.5 0.2.6 0.2.7 0.2.8 0.2.9 0.2.10 0.2.11 0.2.12 0.2.13 0.2.14 0.2.15 0.2.16 0.2.17 0.2.18 0.2.19 0.2.20 0.2.21 0.2.22 0.2.23 0.2.24 0.2.25 0.2.26 0.2.27 0.2.28 0.2.29 0.2.30 0.2.31 0.2.32 0.2.33 0.2.34 0.2.35 0.2.36 Website Product: https://github.com/lm-sys/FastChat/ CPE 2.3info 🔒 🔒 🔒 CPE 2.2info 🔒 🔒 🔒 CVSSv4info VulDB Vector: 🔒 VulDB Reliability: 🔍 CVSSv3info VulDB Meta Base Score: 5.3 VulDB Meta Temp Score: 4.8 VulDB Base Score: 5.3 VulDB Temp Score: 4.8 VulDB Vector: 🔒 VulDB Reliability: 🔍 CVSSv2info Vector Complexity Authentication Confidentiality Integrity Availability Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock VulDB Base Score: 🔒 VulDB Temp Score: 🔒 VulDB Reliability: 🔍 Exploitinginfo Class: Control flow CWE: CWE-670 CAPEC: 🔒 ATT&CK: 🔒 Physical: No Local: No Remote: Yes Availability: 🔒 Access: Public Status: Proof-of-Concept Download: 🔒 Price Prediction: 🔍 Current Price Estimation: 🔒 0-Day Unlock Unlock Unlock Unlock Today Unlock Unlock Unlock Unlock Threat Intelligenceinfo Interest: 🔍 Active Actors: 🔍 Active APT Groups: 🔍 Countermeasuresinfo Recommended: no mitigation known Status: 🔍 0-Day Time: 🔒 Timelineinfo 04/19/2026 Advisory disclosed 04/19/2026 +0 days VulDB entry created 04/19/2026 +0 days VulDB entry last update Sourcesinfo Product: github.com Advisory: 3834 Status: Not defined CVE: CVE-2026-6608 (🔒) GCVE (CVE): GCVE-0-2026-6608 GCVE (VulDB): GCVE-100-358243 scip Labs: https://www.scip.ch/en/?labs.20161013 Entryinfo Created: 04/19/2026 18:04 Changes: 04/19/2026 18:04 (58) Complete: 🔍 Submitter: Eric-f Cache ID: 99:CDC:101 Submitinfo Accepted Submit #792228: LM-Sys FastChat <= 0.2.36 Content Moderation Bypass (CWE-670) (by Eric-f) Discussion No comments yet. Languages: en. Please log in to comment. ◂ PreviousOverviewNext ▸