{"id":"CVE-2026-52807","aliases":["GHSA-vcm5-gvmp-78mp","GO-2026-5661"],"url":"https://o3.security/vulnerability/CVE-2026-52807","summary":"Gogs: DOM-based XSS via Milestone Name on New Issue Page","details":"### Summary\nThe fix for GHSA-vgjm-2cpf-4g7c (DOM-based XSS via milestone selection) was only applied to `templates/repo/issue/view_content.tmpl` but not to `templates/repo/issue/new_form.tmpl`. An attacker can store an HTML/JavaScript payload in a milestone name, and when any user opens the New Issue page and interacts with the milestone dropdown, the payload executes in their browser via Semantic UI's `preserveHTML` behavior.\n\n### Details\nGHSA-vgjm-2cpf-4g7c was patched by adding `| Sanitize` (bluemonday HTML tag stripping) to milestone name rendering in `view_content.tmpl`. However, the same milestone dropdown exists in `new_form.tmpl` and was **not** patched.\n\nIn `new_form.tmpl`, milestone names are rendered with Go's default auto-escaping (`{{.Name}}`), which converts `<` to `&lt;` etc. This prevents direct HTML injection. However, when the browser renders the DOM, the text content of the element contains the **decoded** original payload (e.g., `<img src=x onerror=alert(1)>`).\n\nSemantic UI 2.4.2's dropdown component has `preserveHTML: true` as the default setting. When a user selects a dropdown item, the internal `set.text()` method calls jQuery's `.html()` with the item's text content. This re-parses the decoded text as HTML, creating the injected element and triggering the JavaScript event handler.\n\n### PoC\n[poc.zip](https://github.com/user-attachments/files/26508268/poc.zip)\nPlease extract the uploaded compressed file before proceeding\n\n1. docker compose up --build\n\n<img width=\"1325\" height=\"315\" alt=\"스크린샷 2026-04-06 오후 9 34 05\" src=\"https://github.com/user-attachments/assets/87895cce-5b8e-4320-829a-87a5890cc0d9\" />\n\n### Impact\n- Stored DOM XSS: Any user with write access to a repository can create a malicious milestone. Any other user who visits the New Issue page and interacts with the milestone dropdown will have arbitrary JavaScript executed in their browser session.\n- Session hijacking: The attacker can steal session cookies, perform actions as the victim, or escalate privileges.","published":"2026-06-24T20:25:49.230Z","modified":"2026-10-28T02:30:24.044031510Z","cvss":null,"epss":{"score":0.00483,"percentile":0.40254,"asOf":"2026-09-12"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Go","name":"gogs.io/gogs","fixedVersion":"0.14.3"}],"fix":{"url":"https://github.com/gogs/gogs/commit/573eacdc658641487f8ad883da96b29ec8e2852d","label":"gogs/gogs@573eacd"},"references":[{"type":"WEB","url":"https://github.com/gogs/gogs/releases/tag/v0.14.3"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/52xxx/CVE-2026-52807.json"},{"type":"ADVISORY","url":"https://github.com/gogs/gogs/security/advisories/GHSA-vcm5-gvmp-78mp"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-52807"},{"type":"FIX","url":"https://github.com/gogs/gogs/commit/573eacdc658641487f8ad883da96b29ec8e2852d"},{"type":"FIX","url":"https://github.com/gogs/gogs/pull/8325"},{"type":"PACKAGE","url":"https://github.com/gogs/gogs"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-28T02:30:24.044031510Z"}}