CVE-2026-55418
FastGPT <v4.15.0-beta5 allows cross-tenant S3 file access
Is CVE-2026-55418 being exploited?
Not confirmed. CVE-2026-55418 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.48% probability of exploitation in the next 30 days.
How severe is CVE-2026-55418?
CVE-2026-55418 is rated High with a CVSS score of 8.6. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-55418?
Yes. A fix has been recorded for CVE-2026-55418. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-55418 affect?
CVE-2026-55418 affects FastGPT < v4.15.0-beta5, Self-hosted FastGPT using S3 storage, AWS S3 buckets used by FastGPT. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-55418?
Upgrade to v4.15.0-beta5, validate S3 key ownership and rotate exposed keys.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Attacker can supply another team's S3 key to retrieve/read other tenants' objects via presign or dataset preview endpoints, enabling data exfiltration.
Immediate action required
- affected< 4.15.0-beta5
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.