Advisory details:
github_osv / GHSA-x5qj-865h-mgvm
| Advisory ID | github_osv/GHSA-x5qj-865h-mgvm |
| Aliases |
CVE-2026-48761
|
| Summary | Symfony: HtmlSanitizer UrlAttributeSanitizer Misses URL Attributes ### Description `Symfony\Component\HtmlSanitizer\Visitor\AttributeSanitizer\UrlAttributeSanitizer::getSupportedAttributes()` enumerates the attribute names whose values are scrubbed through `UrlSanitizer::sanitize()` (scheme and host allow-lists, `javascript:` rejection, BiDi check, etc.). The list is `['src', 'href', 'lowsrc', 'background', 'ping', 'action', 'formaction', 'poster', 'cite']`. Other URL-bearing attributes are absent: `<object data=…>`, `<applet codebase=…>`, `<applet archive=…>` and `<object archive=…>`, `<iframe longdesc=…>` and `<img longdesc=…>`. When an integrator opts these elements/attributes in via `allowElement('object', ['data'])`, `allowElement('applet', ['codebase'])`, etc., or via `allowAttribute()`, no URL sanitization runs: `data="javascript:alert(1)"` and similar payloads ship through unchanged into the output, enabling stored XSS. `<meta http-equiv="refresh" content="0; url=…">` is the same class of bug routed differently: the URL is embedded inside a multi-field `content` attribute that the per-attribute sanitizer cannot detect from the attribute name alone. Integrators who enable `<meta>` with the `content` attribute (e.g. via `allowStaticElements()`) see `content="0; url=javascript:alert(1)"` pass through, producing a refresh-driven navigation to a `javascript:` URL. Default configurations are not affected: `<object>`, `<applet>` and `<iframe>` are not in `W3CReference::BODY_ELEMENTS` and `<meta>` requires an explicit opt-in to `<head>` context. The vulnerability surface is integrators who explicitly allow any of those elements together with the listed URL-bearing attributes. ### Resolution `UrlAttributeSanitizer` now also routes `data`, `codebase`, `archive` and `longdesc` through `UrlSanitizer::sanitize()`. A new `MetaRefreshAttributeSanitizer` registered as a default attribute sanitizer detects the `<delay>; url=<url>` syntax inside `<meta content>`, sanitizes the embedded URL, and drops the attribute if the URL is rejected; non-refresh meta `content` values are passed through unchanged. The patches for this issue are available [here](https://github.com/symfony/symfony/commit/069a70f9f26e61e9de3b7f9a864a86ed24b36bd0) for branch 6.4 (and forward-ported to 7.4, 8.0 and 8.1). ### Credits Symfony would like to thank Scott Arciszewski (Trail of Bits) for reporting the issue and Nicolas Grekas for providing the fix. |
| Status | Published |
| Exploitability | 0.5 |
| Weighted Severity | 4.8 |
| Risk | 2.4 |
| Affected and Fixed Packages | Package Details |
| Introduced and Fixed Package Commit Patches | Package Commit Patches Details |
| System | Score | Found at |
|---|---|---|
| cvssv4 | 5.3 | https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/06/GHSA-x5qj-865h-mgvm/GHSA-x5qj-865h-mgvm.json |
| generic_textual | MODERATE |
No EPSS data available for this advisory.
| Patch URL | |
|---|---|
| There are no known patches. | |
| Attack Vector (AV) | Attack Complexity (AC) | Attack Requirements (AT) | Privileges Required (PR) | User Interaction (UI) | Vulnerable System Impact Confidentiality (VC) | Vulnerable System Impact Integrity (VI) | Vulnerable System Impact Availability (VA) | Subsequent System Impact Confidentiality (SC) | Subsequent System Impact Integrity (SI) | Subsequent System Impact Availability (SA) |
|---|---|---|---|---|---|---|---|---|---|---|
network adjacent local physical |
low high |
none present |
none low high |
none passive active |
high low none |
high low none |
high low none |
high low none |
high low none |
high low none |
Vector: SSVCv2/E:N/A:N/T:P/P:M/B:A/M:M/D:T/2026-07-21T18:02:08Z/
Decision: Track
Source URL: https://github.com/cisagov/vulnrichment/blob/develop/2026/48xxx/CVE-2026-48761.json
Source Advisory: vulnrichment/CVE-2026-48761
[{'Exploitation': 'none'},
{'Automatable': 'no'},
{'Technical Impact': 'partial'},
{'Mission Prevalence': 'minimal'},
{'Public Well-being Impact': 'material'},
{'Mission & Well-being': 'medium'}]