CVE-2026-55876

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.

• CWE-79

• https://github.com/HeliumEdu/platform/commit/f0de5c985c701942758b805a3d11dfb008a6af88
• https://github.com/HeliumEdu/platform/security/advisories/GHSA-7r65-76fw-ch5c
• https://github.com/HeliumEdu/platform/security/advisories/GHSA-7r65-76fw-ch5c

Published

Oct 15, 2026

Last Modified

Oct 21, 2026

Status

Deferred

• How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
• Autonomous PentestingAI agents that find and validate exploitable vulnerabilities like this one across your applications.
• PR ReviewsPentest every pull request so vulnerable code is caught before it ships to production.
• AI Penetration TestingHow AI-driven penetration testing continuously covers your attack surface.

• CVE-2026-55870GoCD is a continuous deliver server. Prior to 26.1.0, GoCD c…2.3
• CVE-2026-55871GYM One is open-source gym management software for fitness c…6.5
• CVE-2026-55872GYM One is open-source gym management software for fitness c…8.7
• CVE-2026-55873SeaweedFS is a distributed storage system. In versions 4.08 …4.3
• CVE-2026-55874SeaweedFS is a distributed storage system. Prior to 4.34, th…7.7
• CVE-2026-55875Helium is a free online student planner for classes, homewor…4.3
• CVE-2026-55877Symfony UX is a JavaScript ecosystem for Symfony. From 2.17.…6.1
• CVE-2026-55878Symfony UX is a JavaScript ecosystem for Symfony. From 2.32.…7.8
• CVE-2026-55879OpenReplay is a self-hosted session replay suite. From 1.24.…9.3
• CVE-2026-5588Use of a Broken or Risky Cryptographic Algorithm vulnerabili…7.5
• CVE-2026-55880OpenReplay is a self-hosted session replay suite. In 1.27.0 …7.1
• CVE-2026-55881OpenReplay is a self-hosted session replay suite. From 1.22.…7.1