CVE-2026-55418 FastGPT: S3 presign/read handlers do not bind the object key to the caller's team (cross-team file disclosure)
Attackers can access other teams' files by manipulating S3 object keys in presign or preview requests, leading to cross-team data disclosure.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-55418?
CVE-2026-55418 is a high-severity missing authorization vulnerability in labring FastGPT, published on 7 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-639
Which versions are affected by CVE-2026-55418?
How do I fix CVE-2026-55418?
No fix has been published for CVE-2026-55418 yet. Limit exposure of the affected software until one is available.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-55418 being exploited?
There is no known exploitation of CVE-2026-55418 in the wild and no public exploit code.
Sources
Also known as GHSA-6rxv-p43w-mmx5.