{"id":"CVE-2026-42261","state":"PUBLISHED","title":"PromptHub: Authenticated SSRF via IPv6 filter bypass in `POST /api/skills/fetch-remote`","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.","publishedAt":"2026-05-08T03:11:25.305Z","updatedAt":"2026-05-11T18:11:16.696Z","severity":{"score":7.1,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["legeling PromptHub"],"affected":[{"vendor":"legeling","product":"PromptHub","versions":[{"version":">= 0.4.9, < 0.5.4","status":"affected"}]}],"references":["https://github.com/legeling/PromptHub/security/advisories/GHSA-9fhh-fjfg-5mr6","https://github.com/legeling/PromptHub/releases/tag/v0.5.4"],"weaknesses":["CWE-20","CWE-693","CWE-918"],"ingestedAt":"2026-10-29T20:11:57.932Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/42xxx/CVE-2026-42261.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-42261","state":"PUBLISHED","datePublished":"2026-05-08T03:11:25.305Z","dateUpdated":"2026-05-11T18:11:16.696Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-04-26T11:53:27.705Z"},"containers":{"cna":{"title":"PromptHub: Authenticated SSRF via IPv6 filter bypass in `POST /api/skills/fetch-remote`","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"legeling","product":"PromptHub","versions":[{"version":">= 0.4.9, < 0.5.4","status":"affected"}]}],"references":[{"url":"https://github.com/legeling/PromptHub/security/advisories/GHSA-9fhh-fjfg-5mr6","name":"https://github.com/legeling/PromptHub/security/advisories/GHSA-9fhh-fjfg-5mr6","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/legeling/PromptHub/releases/tag/v0.5.4","name":"https://github.com/legeling/PromptHub/releases/tag/v0.5.4","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":7.1,"baseSeverity":"HIGH","confidentialityImpact":"HIGH","integrityImpact":"LOW","privilegesRequired":"LOW","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-20","lang":"en","description":"CWE-20: Improper Input Validation","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-693","lang":"en","description":"CWE-693: Protection Mechanism Failure","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-918","lang":"en","description":"CWE-918: Server-Side Request Forgery (SSRF)","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-05-08T03:11:25.305Z"},"source":{"advisory":"GHSA-9fhh-fjfg-5mr6","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/legeling/PromptHub/security/advisories/GHSA-9fhh-fjfg-5mr6","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-05-11T18:10:25.854871Z","id":"CVE-2026-42261","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-05-11T18:11:16.696Z"}}]}}}