CVE-2026-110628: Kan 0.5.5 through 0.6.0 Unauthenticated SSRF via /api/download/attatchment

Severity: high (CVSS 8.6 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-14 · updated 2026-10-16
Weakness: CWE-918

Description

Kan 0.5.5 through 0.6.0 contains an unauthenticated server-side request forgery vulnerability in the /api/download/attatchment route due to an incomplete fix for CVE-2026-32255. When S3_ENDPOINT is unset, attackers can pass arbitrary url query parameters to fetch() to read internal services, localhost ports, and cloud instance metadata.

Affected products

kanbn kan: from 0.5.5 through 0.6.0

References

https://github.com/kanbn/kan
https://github.com/kanbn/kan/blob/v0.6.0/.env.example#L25-L27
https://github.com/kanbn/kan/blob/v0.6.0/apps/web/src/pages/api/download/attatchment.ts#L21-L52
https://github.com/kanbn/kan/commit/53397d8e81dc1494d94132848c1f0416f1152bd7
https://github.com/kanbn/kan/pull/590
https://github.com/kanbn/kan/security/advisories/GHSA-qrx8-9hc6-jvqg
https://hackmd.io/@leediay/HyIxU63ofg
https://www.vulncheck.com/advisories/kan-0.5.5-through-0.6.0-unauthenticated-ssrf-via-api-download-attatchment

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