---
id: CVE-2026-55876
title: >-
  Helium is a free online student planner for classes, homework, grades, and
  notes
summary: >-
  Helium is a free online student planner for classes, homework, grades, and
  notes. Prior to 2.2.60, the POST /planner/attachments/ endpoint allows
  authenticated users to upload SVG and HTML attachments because
  conf/configs/common.py omits…
severity: low
cvss: 3.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N'
cwe:
  - CWE-79
vendor: HeliumEdu
product: platform
affected:
  - platform < 2.2.60
published: '2026-10-15'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T18:17:28.307'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-55876'
references:
  - url: >-
      https://github.com/HeliumEdu/platform/commit/f0de5c985c701942758b805a3d11dfb008a6af88
    label: security-advisories@github.com
  - url: >-
      https://github.com/HeliumEdu/platform/security/advisories/GHSA-7r65-76fw-ch5c
    label: security-advisories@github.com
tags:
  - nvd
  - cve.org
ingestedAt: '2026-10-15T18:23:58.451Z'
---

## Overview

Helium is a free online student planner for classes, homework, grades, and notes. Prior to 2.2.60, the POST /planner/attachments/ endpoint allows authenticated users to upload SVG and HTML attachments because conf/configs/common.py omits those formats from BLOCKED_ATTACHMENT_EXTENSIONS and BLOCKED_ATTACHMENT_MIME_TYPES, and helium/planner/serializers/attachmentserializer.py relies on those blocklists. An uploaded SVG served as image/svg+xml can execute embedded script when a visitor opens its public attachment URL, allowing persistent attacker-controlled active content and phishing under an application-managed storage URL. The attachment storage uses a separate origin from the application, so same-origin policy prevents the script from reading application cookies or storage, and application-session compromise is not supported by the maintained deployment configuration. This issue is fixed in version 2.2.60.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.