{"id":"CVE-2026-72832","aliases":["GHSA-269c-h76q-8cxw"],"url":"https://o3.security/vulnerability/CVE-2026-72832","summary":"Grav before 2.0.13 Stored XSS via quoted-attribute bypass","details":"### Summary\n\nA page editor without `admin.super` can place an event handler after a `>` inside a quoted attribute. Grav accepts and stores the page, then executes the handler in the application origin when a visitor opens it.\n\n### Details\n\n`Security::detectXss()` (`system/src/Grav/Common/Security.php:253`) anchors the `on_events` scan at `<` and uses `[^>]*?`, which cannot cross the first literal `>`. When that character is inside a quoted value, the browser keeps the tag open and parses the later `onerror` attribute, so the detector and browser disagree. `AdminController::savePage()` relies on this detector when saving content from page editors outside the `admin.super` whitelist.\n\n### PoC\n\nI reproduced this with `getgrav/grav` 2.0.11 (`ad9709f865b09b68798fb1ac375b484a8cc1d892`), Admin 1.10.52, and Quark 2 1.1.4.\n\n1. Sign in as a user with `admin.login` and `admin.pages`, but without `admin.super`.\n2. Create or edit `/xsstest` and save this page body:\n\n```html\n<img src=x title=\">\" onerror=alert(document.domain)>\n```\n\n3. Open `/xsstest` in a private browser window.\n\nThe save succeeds and the visitor sees an alert containing the site domain. With the body changed to `<img src=x onerror=alert(1)>`, the same endpoint rejects it with `XSS issue detected` and does not store it.\n\n### Impact\n\nA page editor can execute JavaScript in the origin of every user who views the stored page, including unauthenticated visitors.\n\n### Anticipated objection and response\n\nAlthough the `detectXss()` docblock describes it as a heuristic that cannot catch every XSS, this check is the storage-time boundary for page editors outside the default `security.xss_whitelist` of `admin.super`. The same endpoint rejects a plain handler but accepts this executable form, allowing a lower-trust editor to cross the boundary the check is intended to enforce.\n\n### Suggested fix\n\nPrefer an HTML tokenizer or sanitizer that rejects event-handler attributes on parsed elements. If the existing tripwire remains, make its tag scan quote-aware instead of treating every `>` as a boundary. Add double-quoted and single-quoted regression cases plus the rejected plain-handler control.","published":"2026-08-14T11:35:38.484Z","modified":"2026-10-30T10:47:20.031929229Z","cvss":null,"epss":{"score":0.0018,"percentile":0.07829,"asOf":"2026-09-16"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Packagist","name":"getgrav/grav","fixedVersion":"2.0.13"}],"fix":{"url":"https://github.com/getgrav/grav/commit/ad9709f865b09b68798fb1ac375b484a8cc1d892","label":"getgrav/grav@ad9709f"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/72xxx/CVE-2026-72832.json"},{"type":"ADVISORY","url":"https://github.com/getgrav/grav/security/advisories/GHSA-269c-h76q-8cxw"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-72832"},{"type":"ADVISORY","url":"https://www.vulncheck.com/advisories/grav-before-stored-xss-via-quoted-attribute-bypass"},{"type":"FIX","url":"https://github.com/getgrav/grav/commit/ad9709f865b09b68798fb1ac375b484a8cc1d892"},{"type":"PACKAGE","url":"https://github.com/getgrav/grav"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-30T10:47:20.031929229Z"}}