{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "versions": [
              {
                "introduced": "v0.8.2-rc1"
              },
              {
                "last_affected": "v0.8.3-rc1"
              }
            ]
          },
          "events": [
            {
              "introduced": "da108155663f8aaab4e9d83e8a45aba273f0f7aa"
            },
            {
              "last_affected": "9eeec6bc4f5e856ac65f50784254d484b2808622"
            }
          ],
          "repo": "https://github.com/danny-avila/librechat",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-pmw7-gqwj-f954"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-200"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31951.json"
  },
  "details": "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.",
  "id": "CVE-2026-31951",
  "modified": "2026-04-01T23:09:05.880482620Z",
  "published": "2026-03-27T19:29:25.892Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31951.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/danny-avila/LibreChat/security/advisories/GHSA-pmw7-gqwj-f954"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-31951"
    }
  ],
  "schema_version": "1.7.3",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:N/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "LibreChat's MCP Server Header Injection Enables OAuth Token Theft"
}