Auth bypass in Labring Fastgpt
CVE-2026-55418
FastGPT is an open source AI knowledge base platform. Prior to v4.15.0-beta5, two FastGPT file handlers authorize an unrelated resource and then sign or read an S3 object using a key taken directly from the request, without checking that the key belongs to the caller's team. Because S3 object keys are global within the bucket and carry the tenant id only as a path segment, an attacker can supply another team's key and obtain its file contents through the chat-file presign endpoint or dataset preview endpoint. This issue is fixed in version v4.15.0-beta5.
Vulnerability class: IDOR (Insecure Direct Object Reference)
EPSS: 0.003 (22.6th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 8.6 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N.
Affected products
- Labring Fastgpt — versions < 4.15.0-beta5
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM)
- security-advisories@github.com (x_refsource_MISC)
- security-advisories@github.com (x_refsource_MISC)
- security-advisories@github.com (x_refsource_MISC)
Frequently asked questions
- What is CVE-2026-55418?
- CVE-2026-55418 is a high-severity vulnerability in Labring Fastgpt, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 8.6/10. Published 2026-07-07.
- How severe is CVE-2026-55418?
- High severity. CVSS v3 base score is 8.6 out of 10.