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Review reviewHigh

CVE-2026-61684

labring FastGPT

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 INVOKE_TOKEN_SECRET, 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.

CVSS
8.8
EPSS
-
- percentile
CISA KEV
Not listed
Published
2026.07.16
PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV
Exploit probability-
Technical severityCVSS 8.8

Vulnerability overview

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 INVOKE_TOKEN_SECRET, 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.

Affected product and versions

Product
labring FastGPT
Affected versions
>= = 4.15.0-beta4
Fixed versions
No verified fixed-version field is available yet

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
  1. 1
    Identify

    Confirm that labring FastGPT and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CWE
CWE-798