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Concorde CSRF vulnerability due to insecure configuration of authentication cookie attributes

Type: advisorySources: OSV

Concorde, formerly know as Nexkey, is a fork of the federated microblogging platform Misskey. Due to a lack of CSRF countermeasures and improper settings of cookies for MediaProxy authentication, there is a vulnerability that allows MediaProxy authentication to be bypassed. In versions prior to 12.25Q1.1, the authentication cookie does not have the SameSite attribute. This allows an attacker to bypass MediaProxy authentication and load any image without restrictions under certain circumstances. In versions prior to 12.24Q2.3, this cookie was also used to authenticate the job queue management page (bull-board), so bull-board authentication is also bypassed. This may enable attacks that have a significant impact on availability and integrity. The affected versions are too old to be covered by this advisory, but the maintainers of Concorde strongly recommend not using older versions. Version 12.25Q1.1 contains a patch. There is no effective workaround other than updating.

Products
Not specified
Affected versions
Not specified
Fixed versions
Not specified
CVEs
CVE-2025-24900
Confirmed fixed CVEs
Not specified
Updated in this feed
3 Nov 2026, 16:50 UTC · Revision 1

Source evidence

Concorde CSRF vulnerability due to insecure configuration of authentication cookie attributes

core-osv · Original source

Published 11 Feb 2025, 15:36 UTC

Concorde, formerly know as Nexkey, is a fork of the federated microblogging platform Misskey. Due to a lack of CSRF countermeasures and improper settings of cookies for MediaProxy authentication, there is a vulnerability that allows MediaProxy authentication to be bypassed. In versions prior to 12.25Q1.1, the authentication cookie does not have the SameSite attribute. This allows an attacker to bypass MediaProxy authentication and load any image without restrictions under certain circumstances. In versions prior to 12.24Q2.3, this cookie was also used to authenticate the job queue management page (bull-board), so bull-board authentication is also bypassed. This may enable attacks that have a significant impact on availability and integrity. The affected versions are too old to be covered by this advisory, but the maintainers of Concorde strongly recommend not using older versions. Version 12.25Q1.1 contains a patch. There is no effective workaround other than updating.

osv:CVE-2025-24900
Complete source record
{
  "id": "ea603b3c6b3daf9ecdaaacf023db77b69f1122988dd3df22fb7ad1049127e661",
  "url": "https://osv.dev/vulnerability/CVE-2025-24900",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Concorde CSRF vulnerability due to insecure configuration of authentication cookie attributes",
    "summary": "Concorde, formerly know as Nexkey, is a fork of the federated microblogging platform Misskey. Due to a lack of CSRF countermeasures and improper settings of cookies for MediaProxy authentication, there is a vulnerability that allows MediaProxy authentication to be bypassed. In versions prior to 12.25Q1.1, the authentication cookie does not have the SameSite attribute. This allows an attacker to bypass MediaProxy authentication and load any image without restrictions under certain circumstances. In versions prior to 12.24Q2.3, this cookie was also used to authenticate the job queue management page (bull-board), so bull-board authentication is also bypassed. This may enable attacks that have a significant impact on availability and integrity. The affected versions are too old to be covered by this advisory, but the maintainers of Concorde strongly recommend not using older versions. Version 12.25Q1.1 contains a patch. There is no effective workaround other than updating.",
    "evidence": "osv:CVE-2025-24900",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2025-24900",
      "aliases": [
        "CVE-2025-24900",
        "GHSA-5hgq-9vw8-7v87"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/nexryai/concorde",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "5bae3fd373c2cf78245c574824d77d8d3fce3dac"
                },
                {
                  "fixed": "2309b4a292828ddba4d57cf0e914bc433095871d"
                },
                {
                  "fixed": "f3f54bde6a37ad310f83ae46de54a286c4b74059"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "12.25Q1.1"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "fixed": "2309b4a292828ddba4d57cf0e914bc433095871d"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "f3f54bde6a37ad310f83ae46de54a286c4b74059"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v12.24Q4.2",
            "v12.24Q4.1",
            "v12.24Q3.2",
            "v12.24Q3.1",
            "v12.24Q2.6",
            "v12.24Q2.5",
            "v12.24Q2.4",
            "v12.24Q2.3",
            "v12.24Q2.2",
            "v12.24Q2.1-fix",
            "v12.24Q2.1",
            "12.119.2-fix.5.5",
            "12.119.2-fix.5.4",
            "12.119.2-fix.5.3",
            "12.119.2-fix.5.2",
            "12.119.2-fix.5.1",
            "12.119.2-fix.5",
            "12.119.2-fix.4",
            "12.119.2-fix.3",
            "12.119.2-fix.2",
            "12.119.2-fix.1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-24900.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:30.599888100Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/24xxx/CVE-2025-24900.json",
        "https://github.com/nexryai/concorde/security/advisories/GHSA-5hgq-9vw8-7v87",
        "https://nvd.nist.gov/vuln/detail/CVE-2025-24900",
        "https://github.com/nexryai/concorde/commit/2309b4a292828ddba4d57cf0e914bc433095871d",
        "https://github.com/nexryai/concorde/commit/f3f54bde6a37ad310f83ae46de54a286c4b74059"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-352"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/24xxx/CVE-2025-24900.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2025-24900",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 497575,
  "published_at": "2025-02-11T15:36:16.868+00:00"
}