Vulnerability · Published Oct 15, 2026 · Assigned by GitHub_M
CVE-2026-55875Helium: SSRF via External Calendar URL Allows Authenticated Users to Probe Internal Network
Medium 4.3
In plain English
A medium-severity server-side request forgery in platform from HeliumEdu. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 11% of all known vulnerabilities).
Official description
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 products (as reported)
Weakness: CWE-918 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N