{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-6608", "assignerOrgId": "1af790b2-7ee1-4545-860a-a788eba489b5", "state": "PUBLISHED", "assignerShortName": "VulDB", "dateReserved": "2026-04-19T15:59:43.122Z", "datePublished": "2026-04-20T05:15:12.337Z", "dateUpdated": "2026-04-20T05:15:12.337Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "1af790b2-7ee1-4545-860a-a788eba489b5", "shortName": "VulDB", "dateUpdated": "2026-04-20T05:15:12.337Z"}, "title": "lm-sys fastchat Arena Side-by-Side View add_text control flow", "problemTypes": [{"descriptions": [{"type": "CWE", "cweId": "CWE-670", "lang": "en", "description": "Incorrect Control Flow"}]}], "affected": [{"vendor": "lm-sys", "product": "fastchat", "versions": [{"version": "0.2.0", "status": "affected"}, {"version": "0.2.1", "status": "affected"}, {"version": "0.2.2", "status": "affected"}, {"version": "0.2.3", "status": "affected"}, {"version": "0.2.4", "status": "affected"}, {"version": "0.2.5", "status": "affected"}, {"version": "0.2.6", "status": "affected"}, {"version": "0.2.7", "status": "affected"}, {"version": "0.2.8", "status": "affected"}, {"version": "0.2.9", "status": "affected"}, {"version": "0.2.10", "status": "affected"}, {"version": "0.2.11", "status": "affected"}, {"version": "0.2.12", "status": "affected"}, {"version": "0.2.13", "status": "affected"}, {"version": "0.2.14", "status": "affected"}, {"version": "0.2.15", "status": "affected"}, {"version": "0.2.16", "status": "affected"}, {"version": "0.2.17", "status": "affected"}, {"version": "0.2.18", "status": "affected"}, {"version": "0.2.19", "status": "affected"}, {"version": "0.2.20", "status": "affected"}, {"version": "0.2.21", "status": "affected"}, {"version": "0.2.22", "status": "affected"}, {"version": "0.2.23", "status": "affected"}, {"version": "0.2.24", "status": "affected"}, {"version": "0.2.25", "status": "affected"}, {"version": "0.2.26", "status": "affected"}, {"version": "0.2.27", "status": "affected"}, {"version": "0.2.28", "status": "affected"}, {"version": "0.2.29", "status": "affected"}, {"version": "0.2.30", "status": "affected"}, {"version": "0.2.31", "status": "affected"}, {"version": "0.2.32", "status": "affected"}, {"version": "0.2.33", "status": "affected"}, {"version": "0.2.34", "status": "affected"}, {"version": "0.2.35", "status": "affected"}, {"version": "0.2.36", "status": "affected"}], "cpes": ["cpe:2.3:a:lm-sys:fastchat:*:*:*:*:*:*:*:*"], "modules": ["Arena Side-by-Side View Handler"]}], "descriptions": [{"lang": "en", "value": "A vulnerability was detected in lm-sys fastchat up to 0.2.36. Impacted is the function add_text of the component Arena Side-by-Side View Handler. The manipulation results in incorrect control flow. The attack can be launched remotely. The exploit is now public and may be used. The root cause was fixed in commit 34eca62 for gradio_block_arena_named.py, but three other files were missed."}], "metrics": [{"cvssV4_0": {"version": "4.0", "baseScore": 6.9, "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P", "baseSeverity": "MEDIUM"}}, {"cvssV3_1": {"version": "3.1", "baseScore": 5.3, "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N/E:P/RL:X/RC:R", "baseSeverity": "MEDIUM"}}, {"cvssV3_0": {"version": "3.0", "baseScore": 5.3, "vectorString": "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N/E:P/RL:X/RC:R", "baseSeverity": "MEDIUM"}}, {"cvssV2_0": {"version": "2.0", "baseScore": 5, "vectorString": "AV:N/AC:L/Au:N/C:N/I:P/A:N/E:POC/RL:ND/RC:UR"}}], "timeline": [{"time": "2026-04-19T00:00:00.000Z", "lang": "en", "value": "Advisory disclosed"}, {"time": "2026-04-19T02:00:00.000Z", "lang": "en", "value": "VulDB entry created"}, {"time": "2026-04-19T18:04:52.000Z", "lang": "en", "value": "VulDB entry last update"}], "credits": [{"lang": "en", "value": "Eric-f (VulDB User)", "type": "reporter"}], "references": [{"url": "https://vuldb.com/vuln/358243", "name": "VDB-358243 | lm-sys fastchat Arena Side-by-Side View add_text control flow", "tags": ["vdb-entry", "technical-description"]}, {"url": "https://vuldb.com/vuln/358243/cti", "name": "VDB-358243 | CTI Indicators (IOB, IOC, IOA)", "tags": ["signature", "permissions-required"]}, {"url": "https://vuldb.com/submit/792228", "name": "Submit #792228 | LM-Sys FastChat <= 0.2.36 Content Moderation Bypass (CWE-670)", "tags": ["third-party-advisory"]}, {"url": "https://github.com/lm-sys/FastChat/issues/3834", "tags": ["issue-tracking"]}, {"url": "https://gist.github.com/YLChen-007/e45039d23e698222d887ee09735d9d36", "tags": ["exploit"]}, {"url": "https://github.com/lm-sys/FastChat/", "tags": ["product"]}]}}}

{}

{"cveTags": [], "descriptions": [{"lang": "en", "value": "A vulnerability was detected in lm-sys fastchat up to 0.2.36. Impacted is the function add_text of the component Arena Side-by-Side View Handler. The manipulation results in incorrect control flow. The attack can be launched remotely. The exploit is now public and may be used. The root cause was fixed in commit 34eca62 for gradio_block_arena_named.py, but three other files were missed."}], "id": "CVE-2026-6608", "lastModified": "2026-04-20T06:16:21.733", "metrics": {"cvssMetricV2": [{"acInsufInfo": false, "baseSeverity": "MEDIUM", "cvssData": {"accessComplexity": "LOW", "accessVector": "NETWORK", "authentication": "NONE", "availabilityImpact": "NONE", "baseScore": 5.0, "confidentialityImpact": "NONE", "integrityImpact": "PARTIAL", "vectorString": "AV:N/AC:L/Au:N/C:N/I:P/A:N", "version": "2.0"}, "exploitabilityScore": 10.0, "impactScore": 2.9, "obtainAllPrivilege": false, "obtainOtherPrivilege": false, "obtainUserPrivilege": false, "source": "cna@vuldb.com", "type": "Secondary", "userInteractionRequired": false}], "cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 5.3, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "LOW", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 1.4, "source": "cna@vuldb.com", "type": "Primary"}], "cvssMetricV40": [{"cvssData": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "NONE", "attackVector": "NETWORK", "availabilityRequirement": "NOT_DEFINED", "baseScore": 5.5, "baseSeverity": "MEDIUM", "confidentialityRequirement": "NOT_DEFINED", "exploitMaturity": "PROOF_OF_CONCEPT", "integrityRequirement": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "privilegesRequired": "NONE", "providerUrgency": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "userInteraction": "NONE", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "version": "4.0", "vulnAvailabilityImpact": "NONE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "LOW", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "source": "cna@vuldb.com", "type": "Secondary"}]}, "published": "2026-04-20T06:16:21.733", "references": [{"source": "cna@vuldb.com", "url": "https://gist.github.com/YLChen-007/e45039d23e698222d887ee09735d9d36"}, {"source": "cna@vuldb.com", "url": "https://github.com/lm-sys/FastChat/"}, {"source": "cna@vuldb.com", "url": "https://github.com/lm-sys/FastChat/issues/3834"}, {"source": "cna@vuldb.com", "url": "https://vuldb.com/submit/792228"}, {"source": "cna@vuldb.com", "url": "https://vuldb.com/vuln/358243"}, {"source": "cna@vuldb.com", "url": "https://vuldb.com/vuln/358243/cti"}], "sourceIdentifier": "cna@vuldb.com", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-670"}], "source": "cna@vuldb.com", "type": "Primary"}]}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "0.2.0"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "0.2.1"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "0.2.2"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "0.2.3"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "0.2.4"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "0.2.5"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "0.2.6"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "0.2.7"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "0.2.8"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "0.2.9"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "0.2.10"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "0.2.11"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "0.2.12"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "0.2.13"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "0.2.14"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "0.2.15"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "0.2.16"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "0.2.17"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "0.2.18"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "0.2.19"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "0.2.20"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "0.2.21"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "0.2.22"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "0.2.23"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "0.2.24"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "0.2.25"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "0.2.26"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "0.2.27"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "0.2.28"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "0.2.29"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "0.2.30"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "0.2.31"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "0.2.32"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "0.2.33"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "0.2.34"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "0.2.35"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "0.2.36"}}], "enrichment": {"confidence": 95.0, "confidence_source": "inferred", "scores": [{"score": 95.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "fastchat", "source": "cna", "vendor": "lm-sys"}, "product": "fastchat", "vendor": "lm-sys"}], "analysis": {"en": {"generated_at": "2026-04-20T07:50:34.210638+00:00", "value": {"mitigation_remediation": ["Deploy the official update that includes commit 34eca62 and all additional changes to the remaining affected files.", "If a patch is not yet released, disable the Arena Side\u2011by\u2011Side View functionality or restrict remote access to the add_text endpoint to prevent exploitation.", "Continuously supervise application logs for anomalous control\u2011flow patterns and block or quarantine any suspicious inbound requests targeting the FastChat service."], "summary": {"action": "Immediate Patch", "impact": "Remote control\u2011flow manipulation leading to potential unintended execution"}, "threat_synthesis": {"affected_systems": "FastChat, a conversational\u2011AI framework maintained by lm\u2011sys, is affected in all releases up to and including 0.2.36. Versions beyond 0.2.36 are presumed to incorporate the fix in commit 34eca62, but availability of a comprehensive patch that addresses all missed files has yet to be confirmed.", "description_and_impact": "The flaw resides in the add_text function of the Arena Side\u2011by\u2011Side View handler in FastChat. An attacker can manipulate input to cause the function to alter the normal control flow, producing an unintended sequence of operations. The vulnerability is identified as CWE\u2011670, indicating an incorrect or missing return value that can change the logic of the application. Because the defect propagates through remote API calls, an attacker can trigger the miscontrol flow from outside the host without local privileges. The remote nature and public availability of exploit code elevate the risk for any installation running a version of FastChat before 0.2.37.", "risk_and_exploitability": "The CVSS score of 6.9 places the bug in the moderately severe range, yet its exploitation can have serious consequences because a misdirected control flow can lead to unauthorized operations within the application. With no EPSS score available, the exact likelihood of exploitation in the wild cannot be quantified, but the public release of exploit code means attackers have ready tools to target vulnerable deployments. Furthermore, the fault remains unpatched in three previously overlooked files, so a complete fix has not been rolled out. The combination of remote attack vector, public exploit, and incomplete patching makes this vulnerability a significant risk for entities running older FastChat instances."}}}}, "created": "2026-04-20T07:30:45.395444+00:00", "updated": "2026-04-20T08:00:09.679777+00:00", "vendors": ["lm-sys", "lm-sys$PRODUCT$fastchat"]}