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TI-2026-39987 Aliases CVE-2026-55418

FastGPT: S3 presign/read handlers do not bind the object key to the caller's team (cross-team file disclosure)

Priority MEDIUM 44CWE-639Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Security bypass
Confidentiality · integrity · availability
High · None · None
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-639.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00482 41st percentileScored 2026-11-07
Fix Fixed FastGPT (labring): 4.15.0-beta5

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
labringFastGPTbefore 4.15.0-beta54.15.0-beta5Patch availableCNA
  • FastGPT Vendorlabring Affected before 4.15.0-beta5 Fixed in 4.15.0-beta5 Patch available CNA

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPEVersionsRoleVendor
cpe:2.3:a:fastgpt:fastgpt:*:*:*:*:*:*:*:*——Fastgpt
  • cpe:2.3:a:fastgpt:fastgpt:*:*:*:*:*:*:*:* Versions — — ·Fastgpt

Remediation

  • Fix · CNA FastGPT (labring) Fixed in 4.15.0-beta5

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-55418

References

Other 4

  • TI-2026-30610 FastGPT: Unauthenticated Remote Code Execution (RCE) via code-server Misconfiguration in agent-sandbox CVSS 3.1CRITICAL 9.8
  • TI-2026-48466 FastGPT: Unauthenticated WeChat channel hijack and denial of service via shareId-only authorization CVSS 4.0CRITICAL 9.3
  • TI-2026-44161 FastGPT: Unauthenticated cross-tenant data access via forgeable plugin-invoke JWT (default INVOKE_TOKEN_SECRET='token') CVSS 4.0HIGH 8.8
  • TI-2026-44148 Incorrect authorization in labring FastGPT CVSS 3.1HIGH 7.7
  • TI-2026-39440 FastGPT: SSRF in HTTP-tool OpenAPI schema importer via SwaggerParser $ref (bypasses the isInternalAddress guard) CVSS 3.1HIGH 7.7
  • TI-2026-30646 FastGPT: Uncontrolled Resource Consumption leading to Sandbox Exhaustion CVSS 4.0MEDIUM 6.3
See all 18 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences