CVE-2026-55418
HIGHFastGPT: S3 presign/read handlers do not bind the object key to the caller's team (cross-team file disclosure)
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.
Detection & mitigation playbook
VulnerabilityDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for the affected component. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Remediation status
No patched version of the affected component has shipped for CVE-2026-55418 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Mitigate without a patch
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-55418 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-55418. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-55418 in your dependencies?
O3 detects CVE-2026-55418 across dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.