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Medium

Langfuse Slack OAuth Installation Endpoint Lacks Authentication, Enabling Arbitrary Project Linking

Type: advisorySources: OSV

Langfuse is an open source large language model engineering platform. In versions 3.146.0 and below, the /api/public/slack/install endpoint initiates Slack OAuth using a projectId provided by the client without authentication or authorization. The projectId is preserved throughout the OAuth flow, and the callback stores installations based on this untrusted metadata. This allows an attacker to bind their Slack workspace to any project and potentially receive changes to prompts stored in Langfuse Prompt Management. An attacker can replace existing Prompt Slack Automation integrations or pre-register a malicious one, though the latter requires an authenticated user to unknowingly configure it despite visible workspace and channel indicators in the UI. This issue has been fixed in version 3.147.0.

Products
Not specified
Affected versions
Not specified
Fixed versions
Not specified
CVEs
CVE-2026-24055
Confirmed fixed CVEs
Not specified
Updated in this feed
6 Nov 2026, 00:49 UTC · Revision 1

Source evidence

Langfuse Slack OAuth Installation Endpoint Lacks Authentication, Enabling Arbitrary Project Linking

core-osv · Original source

Published 22 Jan 2026, 03:07 UTC

Langfuse is an open source large language model engineering platform. In versions 3.146.0 and below, the /api/public/slack/install endpoint initiates Slack OAuth using a projectId provided by the client without authentication or authorization. The projectId is preserved throughout the OAuth flow, and the callback stores installations based on this untrusted metadata. This allows an attacker to bind their Slack workspace to any project and potentially receive changes to prompts stored in Langfuse Prompt Management. An attacker can replace existing Prompt Slack Automation integrations or pre-register a malicious one, though the latter requires an authenticated user to unknowingly configure it despite visible workspace and channel indicators in the UI. This issue has been fixed in version 3.147.0.

osv:CVE-2026-24055
Complete source record
{
  "id": "25cdebec9f04c7b32615e8fa038f6fff7b0640d10fece798f4444876e8a8900c",
  "url": "https://osv.dev/vulnerability/CVE-2026-24055",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Langfuse Slack OAuth Installation Endpoint Lacks Authentication, Enabling Arbitrary Project Linking",
    "summary": "Langfuse is an open source large language model engineering platform. In versions 3.146.0 and below, the /api/public/slack/install endpoint initiates Slack OAuth using a projectId provided by the client without authentication or authorization. The projectId is preserved throughout the OAuth flow, and the callback stores installations based on this untrusted metadata. This allows an attacker to bind their Slack workspace to any project and potentially receive changes to prompts stored in Langfuse Prompt Management. An attacker can replace existing Prompt Slack Automation integrations or pre-register a malicious one, though the latter requires an authenticated user to unknowingly configure it despite visible workspace and channel indicators in the UI. This issue has been fixed in version 3.147.0.",
    "evidence": "osv:CVE-2026-24055",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-24055",
      "aliases": [
        "CVE-2026-24055",
        "GHSA-pvq7-vvfj-p98x"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/langfuse/langfuse",
              "type": "GIT",
              "events": [
                {
                  "introduced": "bb9d118853a9c64e2147b9022d9f8b3a561b8789"
                },
                {
                  "fixed": "b520cad77b577ce468b08ef68ce992f8c65b0571"
                },
                {
                  "fixed": "3adc89e4d72729eabef55e46888b8ce80a7e3b0a"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:langfuse:langfuse:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "3.89.0"
                      },
                      {
                        "fixed": "3.147.0"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "range": [
                      {
                        "fixed": "3adc89e4d72729eabef55e46888b8ce80a7e3b0a"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "b520cad77b577ce468b08ef68ce992f8c65b0571"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "v3.147.0"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v3.146.0",
            "v3.145.0",
            "v3.144.0",
            "v3.143.0",
            "v3.142.0",
            "v3.141.0",
            "v3.140.0",
            "v3.139.0",
            "v3.138.0",
            "v3.137.0",
            "v3.136.0",
            "v3.135.1",
            "v3.135.0",
            "v3.134.0",
            "v3.133.0",
            "v3.132.0",
            "v3.131.0",
            "v3.130.0",
            "v3.129.0",
            "v3.128.0",
            "v3.127.0",
            "v3.126.1",
            "v3.126.0",
            "v3.125.0",
            "v3.124.1",
            "v3.124.0",
            "v3.123.1",
            "v3.123.0",
            "v3.122.2",
            "v3.122.1",
            "v3.122.0",
            "v3.121.0",
            "v3.120.0",
            "v3.119.1",
            "v3.119.0",
            "v3.118.0",
            "v3.117.2",
            "v3.117.1",
            "v3.117.0",
            "v3.116.1",
            "v3.116.0",
            "v3.115.0",
            "v3.114.0",
            "v3.113.0",
            "v3.112.0",
            "v3.111.0",
            "v3.110.0",
            "v3.109.0",
            "v3.108.0",
            "v3.107.0",
            "v3.106.4",
            "v3.106.3",
            "v3.106.2",
            "v3.106.1",
            "v3.106.0",
            "v3.105.0",
            "v3.104.0",
            "v3.103.0",
            "v3.102.0",
            "v3.101.0",
            "v3.100.0",
            "v3.99.0",
            "v3.98.2",
            "v3.98.1",
            "v3.98.0",
            "v3.97.5",
            "v3.97.4",
            "v3.97.3",
            "v3.97.2",
            "v3.97.1",
            "v3.97.0",
            "v3.96.2",
            "v3.96.1",
            "v3.96.0",
            "v3.95.2",
            "v3.95.1",
            "v3.95.0",
            "v3.94.0",
            "v3.93.0",
            "v3.92.1",
            "v3.92.0",
            "v3.91.0",
            "v3.90.0",
            "v3.89.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-24055.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:45.727116310Z",
      "provider": "osv",
      "references": [
        "https://github.com/langfuse/langfuse/releases/tag/v3.147.0",
        "https://langfuse.com/docs/prompt-management/features/webhooks-slack-integrations",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/24xxx/CVE-2026-24055.json",
        "https://github.com/langfuse/langfuse/security/advisories/GHSA-pvq7-vvfj-p98x",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-24055",
        "https://github.com/langfuse/langfuse/commit/3adc89e4d72729eabef55e46888b8ce80a7e3b0a"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-284"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/24xxx/CVE-2026-24055.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-24055",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 513621,
  "published_at": "2026-01-22T03:07:03.784+00:00"
}