CVE-2026-42261

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.

CVSS v3 7.1 HIGH

7.1^/10

CVSS v3 : HIGH

Vector :

Exploitability : 2.8 / Impact : 4.2

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required LOW

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact LOW

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://github.com/legeling/PromptHub/releases/tag/v0.5.4	Patch Product
https://github.com/legeling/PromptHub/security/advisories/GHSA-9fhh-fjfg-5mr6	Exploit Mitigation Vendor Advisory
https://github.com/legeling/PromptHub/security/advisories/GHSA-9fhh-fjfg-5mr6	Exploit Mitigation Vendor Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:legeling:prompthub:*:*:*:*:-:*:*:*

History

No history.

Information

Published : 2026-05-08 04:16

Updated : 2026-06-17 10:47

NVD link : CVE-2026-42261

Mitre link : CVE-2026-42261

CVE.ORG link : CVE-2026-42261

JSON object : View

Products Affected

legeling

prompthub

CWE

CWE-20

Improper Input Validation

CWE-693

Protection Mechanism Failure

CWE-918

Server-Side Request Forgery (SSRF)

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