{"id":"CVE-2026-55876","published":"2026-10-15T18:17:28.307","lastModified":"2026-10-16T20:04:29.760","description":"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.","cvssScore":3.5,"cvssSeverity":"LOW","cvssVector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N","cwes":["CWE-79"],"vendors":[],"products":[],"references":[{"url":"https://github.com/HeliumEdu/platform/commit/f0de5c985c701942758b805a3d11dfb008a6af88","tags":[]},{"url":"https://github.com/HeliumEdu/platform/security/advisories/GHSA-7r65-76fw-ch5c","tags":[]}],"exploitRefs":[{"url":"https://github.com/HeliumEdu/platform/commit/f0de5c985c701942758b805a3d11dfb008a6af88","tags":[]},{"url":"https://github.com/HeliumEdu/platform/security/advisories/GHSA-7r65-76fw-ch5c","tags":[]}],"hasPoc":true,"ai":null}