{"id":"CVE-2026-52807","title":"Gogs has DOM-based XSS via Milestone Name on New Issue Page","summary":"Gogs has DOM-based XSS via Milestone Name on New Issue Page","severity":"high","cwe":["CWE-79"],"vendor":"gogs","product":"gogs.io/gogs","ecosystem":"go","affected":["gogs.io/gogs < 0.14.3"],"patched":["gogs.io/gogs 0.14.3"],"published":"2026-06-23","updated":"2026-06-23","source":"GHSA","sourceUrl":"https://github.com/advisories/GHSA-vcm5-gvmp-78mp","references":[{"url":"https://github.com/gogs/gogs/security/advisories/GHSA-vcm5-gvmp-78mp"},{"url":"https://github.com/gogs/gogs/pull/8325"},{"url":"https://github.com/gogs/gogs/commit/573eacdc658641487f8ad883da96b29ec8e2852d"},{"url":"https://github.com/gogs/gogs/releases/tag/v0.14.3"},{"url":"https://github.com/advisories/GHSA-vcm5-gvmp-78mp"}],"tags":["ghsa","go"],"epss":0.00483,"epssPercentile":0.40796,"ingestedAt":"2026-06-29T13:24:35.473Z","slug":"CVE-2026-52807","body":"## Overview\n\n### 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.\n\n## Affected packages\n\n- `gogs.io/gogs < 0.14.3`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `gogs.io/gogs 0.14.3`","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":41.3,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}