{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-31951","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","state":"PUBLISHED","assignerShortName":"GitHub_M","dateReserved":"2026-03-10T15:10:10.657Z","datePublished":"2026-03-27T19:29:25.892Z","dateUpdated":"2026-03-31T13:46:25.297Z"},"containers":{"cna":{"title":"LibreChat's MCP Server Header Injection Enables OAuth Token Theft","problemTypes":[{"descriptions":[{"cweId":"CWE-200","lang":"en","description":"CWE-200: Exposure of Sensitive Information to an Unauthorized Actor","type":"CWE"}]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":6.8,"baseSeverity":"MEDIUM","confidentialityImpact":"HIGH","integrityImpact":"NONE","privilegesRequired":"LOW","scope":"CHANGED","userInteraction":"REQUIRED","vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:N/A:N","version":"3.1"}}],"references":[{"name":"https://github.com/danny-avila/LibreChat/security/advisories/GHSA-pmw7-gqwj-f954","tags":["x_refsource_CONFIRM"],"url":"https://github.com/danny-avila/LibreChat/security/advisories/GHSA-pmw7-gqwj-f954"}],"affected":[{"vendor":"danny-avila","product":"LibreChat","versions":[{"version":">= v0.8.2-rc1, <= v0.8.3-rc1","status":"affected"}]}],"providerMetadata":{"orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","shortName":"GitHub_M","dateUpdated":"2026-03-27T19:29:25.892Z"},"descriptions":[{"lang":"en","value":"LibreChat is a ChatGPT clone with additional features. In versions 0.8.2-rc1 through 0.8.3-rc1, user-created MCP (Model Context Protocol) servers can include arbitrary HTTP headers that undergo credential placeholder substitution. An attacker can create a malicious MCP server with headers containing `{{LIBRECHAT_OPENID_ACCESS_TOKEN}}` (and others), causing victims who call tools on that server to have their OAuth tokens exfiltrated. Version 0.8.3-rc2 fixes the issue."}],"source":{"advisory":"GHSA-pmw7-gqwj-f954","discovery":"UNKNOWN"}},"adp":[{"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-03-31T13:45:16.896153Z","id":"CVE-2026-31951","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-03-31T13:46:25.297Z"}}]}}