CVE-2026-84301 labring CVE debrief

Who should care

Defenders responsible for FastGPT deployments, server-side integrations, and monitoring should assess exposure and prioritize patching and monitoring. This includes reviewing server-side integrations that use the safe-Axios-backed HTTP tool and verifying and applying the patch to version 4.15.2. Additionally, defenders should monitor for potential exploitation attempts and review compensating controls for exposed systems.

Why it matters

CVE-2026-84301 is a vulnerability in FastGPT that allows authenticated attackers to bypass security checks and reach services that would normally be blocked. Defenders should prioritize verifying and applying the patch to version 4.15.2, reviewing server-side integrations, and monitoring for potential exploitation attempts.

• Authenticated attackers can bypass security checks and reach services that would normally be blocked.
• The vulnerability allows for potential exploitation attempts on server-side integrations.
• Defenders need to verify and apply the patch to version 4.15.2 to prevent exploitation.
• The time-of-check/time-of-use gap in the safe Axios request interceptor creates a DNS rebinding window.

Technical summary

The safe Axios request interceptor in FastGPT validates a hostname with isInternalAddress() before a later HTTP connection performs an independent DNS lookup, creating a DNS rebinding window. This allows an attacker-controlled hostname to resolve publicly during the check and to a loopback, private, link-local, or metadata address during connection. The vulnerability affects server-side integrations that use the safe-Axios-backed HTTP tool and allows authenticated attackers to bypass security checks and reach services that would normally be blocked.

Defensive priority

Defenders should prioritize verifying and applying the patch to version 4.15.2, reviewing server-side integrations that use the safe-Axios-backed HTTP tool, and monitoring for potential exploitation attempts.

Recommended defensive actions

• Verify and apply the patch to version 4.15.2
• Review server-side integrations that use the safe-Axios-backed HTTP tool
• Monitor for potential exploitation attempts
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

The CVE record and NVD entry provide details on the vulnerability, including its description, CVSS score, and affected versions. However, the corpus does not establish versions, exploitation, impact, or remediation beyond the provided information.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.