{"id":"CVE-2026-55876","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-55876","generatedAt":"2026-10-28T04:11:24.824Z","title":"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…","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.","published":"2026-10-15T18:17:28.000Z","lastModified":"2026-10-21T01:17:39.000Z","status":"Deferred","sourceIdentifier":"security-advisories@github.com","cvss":{"version":"3.1","score":3.5,"severity":"LOW","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N"},"cwe":["CWE-79"],"affected":[],"epss":{"score":0.00184,"percentile":0.07933,"date":"2026-10-27","history":[{"date":"2026-10-16","score":0.00152,"percentile":0.03974}]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"low","text":"Lower severity and a low EPSS score (0.18%). Track it; it rarely justifies an emergency change on its own."},"changes":[{"kind":"new","label":"New CVE","at":"2026-10-15T18:17:28.000Z","detail":{"score":"3.5","severity":"LOW","publishedAt":"2026-10-15T18:17:28.307Z"},"summary":"New CVE, low severity (CVSS 3.5)."}],"references":[{"url":"https://github.com/HeliumEdu/platform/commit/f0de5c985c701942758b805a3d11dfb008a6af88","source":"security-advisories@github.com"},{"url":"https://github.com/HeliumEdu/platform/security/advisories/GHSA-7r65-76fw-ch5c","source":"security-advisories@github.com"},{"url":"https://github.com/HeliumEdu/platform/security/advisories/GHSA-7r65-76fw-ch5c","source":"134c704f-9b21-4f2e-91b3-4a467353bcc0"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-55876","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}