EUVD-2026-12092Severity by source
AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:L/A:N
Primary rating from GitHub Advisory · only source for this CVE.
CVSS VectorGitHub Advisory
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:L/A:N
Lifecycle Timeline
3DescriptionGitHub Advisory
LibreChat is a ChatGPT clone with additional features. From 0.8.2 to 0.8.2-rc3, The MCP (Model Context Protocol) OAuth callback endpoint accepts the redirect from the identity provider and stores OAuth tokens for the user who initiated the flow, without verifying that the browser hitting the redirect URL is logged in or that the logged-in user matches the initiator. An attacker can send the authorization URL to a victim; when the victim completes the flow, the victim’s OAuth tokens are stored on the attacker’s LibreChat account, enabling account takeover of the victim’s MCP-linked services (e.g. Atlassian, Outlook). This vulnerability is fixed in 0.8.3-rc1.
AnalysisAI
LibreChat versions 0.8.2 through 0.8.2-rc3 contain an authentication bypass vulnerability in the Model Context Protocol (MCP) OAuth callback endpoint that allows attackers to steal OAuth tokens by tricking victims into completing an OAuth flow, resulting in account takeover of the victim's MCP-linked services like Atlassian and Outlook. No active exploitation is known (not in KEV), no POC is publicly available, and EPSS data is not yet available for this newly disclosed vulnerability.
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | LibreChat versions 0.8.2 to 0.8.2-rc3 with MCP OAuth callback endpoint enabled. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 7.6 (High) score reflects significant risk: network-based attack (AV:N), low complexity (AC:L), requires low privileges (PR:L) and user interaction (UI:R), with scope change (S:C) leading to high confidentiality impact (C:H). … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker with a low-privileged LibreChat account initiates an OAuth flow with a target service (e.g., Atlassian Confluence), captures the authorization URL, and sends it to a victim via phishing email or message. When the unsuspecting victim clicks the link and completes authentication with their Atlassian credentials, the OAuth tokens are stored in the attacker's LibreChat account instead of the victim's. … |
| Remediation | Upgrade to LibreChat version 0.8.3-rc1 or later, which contains the fix for this vulnerability. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours: Identify all LibreChat instances running versions 0.8.2 through 0.8.2-rc3 and document their usage scope and connected OAuth services. …
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