FastGPT is a knowledge-based AI application platform. In 4.15.0-beta4, FastGPT plugin invoke reverse-call endpoints under /api/invoke/* authenticate only by verifying a JWT signed with INVOKETOKENSECRET, which defaults to the constant string token and was not set in official deployment templates. An unauthenticated attacker can self-sign an HS256 JWT and reach /api/invoke/userInfo to disclose cross-tenant user PII by attacker-supplied tmbId values, or /api/invoke/fileUpload to write attacker-controlled content into chat files. This issue is fixed in version 4.15.0-beta5.
{
"cwe_ids": [
"CWE-798"
],
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/61xxx/CVE-2026-61684.json",
"cna_assigner": "GitHub_M"
}