Helium: Stored XSS via Unrestricted SVG File Upload — Authenticated Users Can Store Executable Scripts

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-55876
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-15 18:17:28 UTC
Updated2026-10-21 01:17:39 UTC
DescriptionHelium 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.

Risk And Classification

Primary CVSS: v3.1 3.5 LOW from [email protected]

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N

EPSS: 0.001520000 probability, percentile 0.039740000 (date 2026-10-16)

Problem Types: CWE-79 | CWE-79 CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary3.5LOWCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N
3.1CNADECLARED3.5LOWCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
Required
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA HeliumEdu Platform affected < 2.2.60 Not specified

References

ReferenceSourceLinkTags
github.com/HeliumEdu/platform/commit/f0de5c985c701942758b805a3d11dfb008a... [email protected] github.com
github.com/HeliumEdu/platform/security/advisories/GHSA-7r65-76fw-ch5c 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com
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