{"id":"GHSA-vcm5-gvmp-78mp","summary":"Gogs has 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 `\u003c` to `<` 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., `\u003cimg src=x onerror=alert(1)\u003e`).\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\u003cimg 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\" /\u003e\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.","aliases":["CVE-2026-52807","GO-2026-5661"],"modified":"2026-07-21T13:45:21.718040292Z","published":"2026-06-23T17:02:52Z","database_specific":{"github_reviewed_at":"2026-06-23T17:02:52Z","nvd_published_at":"2026-06-24T21:16:56Z","cwe_ids":["CWE-79"],"severity":"MODERATE","github_reviewed":true},"references":[{"type":"WEB","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":"WEB","url":"https://github.com/gogs/gogs/pull/8325"},{"type":"WEB","url":"https://github.com/gogs/gogs/commit/573eacdc658641487f8ad883da96b29ec8e2852d"},{"type":"PACKAGE","url":"https://github.com/gogs/gogs"},{"type":"WEB","url":"https://github.com/gogs/gogs/releases/tag/v0.14.3"}],"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":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/06/GHSA-vcm5-gvmp-78mp/GHSA-vcm5-gvmp-78mp.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X"}]}