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.
Conclusion & alert: CVE-2025-24900 is rated Moderate Risk (44.8/100): CVSS High severity, with low exploitation likelihood (EPSS 0.37%). Mandatory action: Review affected assets and schedule remediation.
Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.
EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).
| # | Date | Old EPSS score | New EPSS score | Delta (New - Old) |
|---|---|---|---|---|
| 1 | 2026-06-15 | 0.05% | 0.37% | +0.32% |
| 2 | 2025-07-11 | 0.05% | 0.05% | +0.01% |
| 3 | 2025-07-10 | — | 0.05% | — |
Full EPSS history (5 records total)
CVSS metrics for this CVE.
| Base score | Version | Severity | Vector | Exploitability | Impact | Score source |
|---|---|---|---|---|---|---|
| 8.6 | 3.1 | HIGH |
|
3.9 | 4.0 | [email protected] |
| Vendor | Product | Version | Raw CPE |
|---|---|---|---|
| No affected products in dataset. | |||