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5.5 KiB
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5.5 KiB
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{"schema_version":"1.9.0","id":"GHSA-jq8v-rmf6-65jw","published":"2026-06-22T23:58:46Z","modified":"2026-07-21T13:30:31.803438481Z","aliases":["CVE-2026-52798","GO-2026-5477"],"summary":"Gogs has Stored XSS in `.ipynb` Preview","details":"# Summary\n\nAlthough `.ipynb` previews are sanitized on the server side via `/-/api/sanitize_ipynb`, the inserted content is **re-rendered on the client side without sanitization** using `marked()` on elements with the `.nb-markdown-cell` class. During this process, links containing schemes such as `javascript:` can be regenerated.\n\nAs a result, when a victim views an attacker-crafted `.ipynb` file and clicks the link, **arbitrary JavaScript is executed in the Gogs origin**, leading to a click-based Stored XSS.\n\n# Details\n\nAfter the rendered output of a `.ipynb` file is sanitized via `/-/api/sanitize_ipynb` and inserted into the DOM, **only the Markdown cell portions are re-rendered using `marked()` and overwritten in the DOM**. During this process, links with the `javascript:` scheme can be regenerated.\n\n`templates/repo/view_file.tmpl:42–71`\n\n```html\n{{else if .IsIPythonNotebook}}\n <script>\n $.getJSON(\"{{.RawFileLink}}\", null, function(notebook_json) {\n var notebook = nb.parse(notebook_json);\n var rendered = notebook.render();\n $.ajax({\n type: \"POST\",\n url: '{{AppSubURL}}/-/api/sanitize_ipynb',\n data: rendered.outerHTML,\n processData: false,\n contentType: false,\n }).done(function(data) {\n $(\"#ipython-notebook\").append(data);\n $(\"#ipython-notebook code\").each(function(i, block) {\n $(block).addClass(\"py\").addClass(\"python\");\n hljs.highlightBlock(block);\n });\n\n // Overwrite image method to append proper prefix to the source URL\n var renderer = new marked.Renderer();\n var context = '{{.RawFileLink}}';\n context = context.substring(0, context.lastIndexOf(\"/\"));\n renderer.image = function (href, title, text) {\n return `<img src=\"${context}/${href}\"`\n };\n $(\"#ipython-notebook .nb-markdown-cell\").each(function(i, markdown) {\n $(markdown).html(marked($(markdown).html(), {renderer: renderer}));\n });\n });\n });\n </script>\n```\n\nWhile **regular HTML pages (including `.ipynb` preview pages)** are served **without a Content Security Policy (CSP)**, CSP headers are applied **only to attachment delivery routes**.\n\n`internal/cmd/web.go:323`\n\n```go\nc.Header().Set(\"Content-Security-Policy\", \"default-src 'none'; style-src 'unsafe-inline'; sandbox\")\n```\n\n\n# Steps to Reproduce\n\n1. As the attacker, add and push/commit a `.ipynb` file containing a `javascript:` link in a Markdown cell to a repository.\n\n * Example (PoC):\n\n ```json\n {\n \"nbformat\": 4,\n \"nbformat_minor\": 2,\n \"metadata\": {},\n \"cells\": [\n {\n \"cell_type\": \"markdown\",\n \"metadata\": {},\n \"source\": [\n \"[poc](javascript:alert(document.domain))\"\n ]\n }\n ]\n }\n ```\n\n2. The victim opens the file on Gogs (e.g., `/<user>/<repo>/src/<branch>/poc.ipynb`).\n<img width=\"2386\" height=\"1218\" alt=\"image\" src=\"https://github.com/user-attachments/assets/b0d93fd8-c5ca-4058-8af0-98dee590d3ad\" />\n\n3. When the victim clicks the `poc` link displayed in the preview, `alert(document.domain)` is executed in the same Gogs origin.\n<img width=\"2390\" height=\"1388\" alt=\"image\" src=\"https://github.com/user-attachments/assets/0eb6ebe8-632c-4a41-8a11-46471514b4c4\" />\n\n# Minimum Required Privileges\n\n* **Attacker**: Ability to place a `.ipynb` file as a **regular (non-admin) user**\n\n * For example: a general user who can create a public repository and add files.\n * Or: write access (collaborator, etc.) to an existing repository that the victim will view.\n* **Victim**: Permission to view the repository (a click is required).\n\n# Impact\n\n* Unauthorized actions performed with the victim’s account privileges (e.g., repository settings changes, Issue operations,誘導 to token creation).\n* Theft of information accessible to the victim (repository/Issue/Wiki contents, tokens exposed in page context).\n* If the victim is an administrator, the impact may escalate to instance-wide configuration changes and user management.","affected":[{"package":{"name":"gogs.io/gogs","ecosystem":"Go","purl":"pkg:golang/gogs.io/gogs"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"0.14.3"}]}],"database_specific":{"last_known_affected_version_range":"<= 0.14.2","source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/06/GHSA-jq8v-rmf6-65jw/GHSA-jq8v-rmf6-65jw.json"}}],"references":[{"type":"WEB","url":"https://github.com/gogs/gogs/security/advisories/GHSA-jq8v-rmf6-65jw"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-52798"},{"type":"WEB","url":"https://github.com/gogs/gogs/pull/8319"},{"type":"WEB","url":"https://github.com/gogs/gogs/commit/17b168b11ca759a7550e1f4bbd68bbde14db7785"},{"type":"PACKAGE","url":"https://github.com/gogs/gogs"},{"type":"WEB","url":"https://github.com/gogs/gogs/releases/tag/v0.14.3"}],"database_specific":{"cwe_ids":["CWE-79"],"github_reviewed":true,"github_reviewed_at":"2026-06-22T23:58:46Z","nvd_published_at":"2026-06-24T21:16:55Z","severity":"HIGH"},"severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:L"}]} |