CVE-2026-55875

CVE-2026-55875 · Helium: SSRF via External Calendar URL Allows Authenticated Users to Probe Internal Network

This page contains facts from public vulnerability sources. Check the original advisory before updating.

Helium is a free online student planner for classes, homework, grades, and notes. Prior to 2.2.60, any authenticated user can submit an arbitrary URL to POST /feed/externalcalendars/, where helium/feed/services/icalexternalcalendarservice.py uses validate_url to check only URL syntax before passing the value to urllib.request.urlopen, and fetch_ical_conditional periodically refetches the stored URL. The server can therefore issue requests to attacker-selected external or internal hosts, while distinct responses, including an uncaught http.client.RemoteDisconnected condition for non-HTTP services, reveal internal host and port reachability. The supported impact is forced outbound requests and internal service reconnaissance; the advisory does not demonstrate secret retrieval because the relevant ECS credentials path is task-specific and unpredictable. This issue is fixed in version 2.2.60.

CVSS 4.3 · Medium · EPSS 0.2%

Published

2026-10-15T17:24:00.931Z

Updated

2026-10-15T17:48:20.682Z

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