CVE-2026-42261 (GCVE-0-2026-42261)
Vulnerability from cvelistv5 – Published: 2026-05-08 03:11 – Updated: 2026-05-11 18:11
VLAI
EPSS
VEX
Title
PromptHub: Authenticated SSRF via IPv6 filter bypass in `POST /api/skills/fetch-remote`
Summary
PromptHub is an all-in-one AI toolbox for prompt, skill, and agent management. From version 0.4.9 to before version 0.5.4, apps/web/src/routes/skills.ts exposes an authenticated endpoint POST /api/skills/fetch-remote that fetches a user-supplied URL server-side and reflects the response body (up to 5 MB) back to the caller. The SSRF protection in apps/web/src/utils/remote-http.ts (isPrivateIPv6) attempts to block private/loopback destinations, but multiple alternate-but-valid IPv6 representations bypass the check. The bypasses reach any IPv4 address (loopback, RFC1918, link-local) via IPv4-mapped IPv6 in hex form, and the canonical ::1 via any representation that isn't the literal string "::1". Any authenticated user (role: user or admin) can trigger the SSRF. On deployments configured with ALLOW_REGISTRATION=true — a supported and documented configuration — this means any internet user who can register. This issue has been patched in version 0.5.4.
Severity
7.1 (High)
SSVC
Exploitation: poc
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-05-11 18:10 UTC
CWE
Assigner
References
2 references
| URL | Tags |
|---|---|
| https://github.com/legeling/PromptHub/security/ad… | x_refsource_CONFIRM |
| https://github.com/legeling/PromptHub/releases/ta… | x_refsource_MISC |
Impacted products
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"title": "PromptHub: Authenticated SSRF via IPv6 filter bypass in `POST /api/skills/fetch-remote`",
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