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

Description (CNA)

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.

Affected (CNA)

Vendor / product	Versions
HeliumEdu / platform	affected < 2.2.60

CWE

CWE-918

References

ADP enrichment

CISA-ADP

No English description supplied.

https://github.com/HeliumEdu/platform/security/advisories/GHSA-2f83-94pv-v3f5