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.

No CVSS v4.0

Attack Vector Network

Attack Complexity Low

Privileges Required Low

Scope Unchanged

Confidentiality Impact High

Integrity Impact Low

Availability Impact None

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

The EPSS score is 0.00055.

Key SSVC decision points have not yet been added.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
legeling PromptHub affected
Version Status Constraints
>= 0.4.9, < 0.5.4 affected —

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Project Subscriptions

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Advisories

No advisories yet.

Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://github.com/legeling/PromptHub/releases/tag/v0.5.4 cve-icon cve-icon
https://github.com/legeling/PromptHub/security/advisories/GHSA-9fhh-fjfg-5mr6 cve-icon cve-icon
History

Fri, 08 May 2026 04:00:00 +0000

Type Values Removed Values Added
Description 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.
Title PromptHub: Authenticated SSRF via IPv6 filter bypass in `POST /api/skills/fetch-remote`
Weaknesses CWE-20
CWE-693
CWE-918
References
Metrics cvssV3_1

{'score': 7.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-05-08T03:11:25.305Z

Reserved: 2026-04-26T11:53:27.705Z

Link: CVE-2026-42261

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-05-08T04:16:20.107

Modified: 2026-05-08T04:16:20.107

Link: CVE-2026-42261

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-05-08T05:30:46Z

Weaknesses