FKIE_CVE-2026-31951

Vulnerability from fkie_nvd - Published: 2026-03-27 20:16 - Updated: 2026-10-26 21:10
Severity
6.8 (Medium) - CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:N/A:N
5.7 (Medium) - CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:N/A:N
Summary
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.
References
security-advisories@github.comhttps://github.com/danny-avila/LibreChat/security/advisories/GHSA-pmw7-gqwj-f954Exploit, Vendor Advisory
Impacted products
Vendor Product Version
librechat librechat *
librechat librechat 0.8.3
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "LibreChat",
          "vendor": "danny-avila",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= v0.8.2-rc1, \u003c= v0.8.3-rc1"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:librechat:librechat:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "0B0F03AD-B51B-4501-B292-3133DBD964A8",
              "versionEndExcluding": "0.8.3",
              "versionStartIncluding": "0.8.2",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:librechat:librechat:0.8.3:rc1:*:*:*:*:*:*",
              "matchCriteriaId": "482D0FE3-2AB3-47B6-982E-564A5B824464",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "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."
    },
    {
      "lang": "es",
      "value": "LibreChat es un clon de ChatGPT con caracter\u00edsticas adicionales. En las versiones 0.8.2-rc1 a 0.8.3-rc1, los servidores MCP (Model Context Protocol) creados por el usuario pueden incluir encabezados HTTP arbitrarios que sufren sustituci\u00f3n de marcadores de posici\u00f3n de credenciales. Un atacante puede crear un servidor MCP malicioso con encabezados que contienen \u2019{{LIBRECHAT_OPENID_ACCESS_TOKEN}}\u2019 (y otros), lo que provoca que las v\u00edctimas que llaman a herramientas en ese servidor vean sus tokens OAuth exfiltrados. La versi\u00f3n 0.8.3-rc2 corrige el problema."
    }
  ],
  "id": "CVE-2026-31951",
  "lastModified": "2026-10-26T21:10:00.170",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "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"
        },
        "exploitabilityScore": 2.3,
        "impactScore": 4.0,
        "source": "security-advisories@github.com",
        "type": "Secondary"
      },
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 5.7,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "NONE",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "REQUIRED",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:N/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 2.1,
        "impactScore": 3.6,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-31951",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-03-31T13:45:16.896153Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-03-27T20:16:30.397",
  "references": [
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Exploit",
        "Vendor Advisory"
      ],
      "url": "https://github.com/danny-avila/LibreChat/security/advisories/GHSA-pmw7-gqwj-f954"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-200"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}



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