Vulnerability · Published Nov 16, 2021 · Assigned by GitHub_M
CVE-2021-41258Cross-site scripting (XSS) from image block content in the site frontend
High 7.3
In plain English
A high-severity cross-site scripting in kirby from getkirby. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.8% (higher than 57% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
Kirby is an open source file structured CMS. In affected versions Kirby's blocks field stores structured data for each block. This data is then used in block snippets to convert the blocks to HTML for use in your templates. We recommend to escape HTML special characters to protect against cross-site scripting (XSS) attacks. The default snippet for the image block unfortunately did not use our escaping helper. This made it possible to include malicious HTML code in the source, alt and link fields of the image block, which would then be displayed on the site frontend and executed in the browsers of site visitors and logged in users who are browsing the site. Attackers must be in your group of authenticated Panel users in order to exploit this weakness. Users who do not make use of the blocks field are not affected. This issue has been patched in Kirby version 3.5.8 by escaping special HTML characters in the output from the default image block snippet. Please update to this or a later version to fix the vulnerability.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Packagist | getkirby/cms | 3.5.8 | GHSA-cq58-r77c-5jjw |
Affected products (as reported)
Weakness: CWE-79 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N
References
- https://github.com/getkirby/kirby/releases/tag/3.5.8 x_refsource_MISC
- https://github.com/getkirby/kirby/security/advisories/GHSA-cq58-r77c-5jjw x_refsource_CONFIRM
- https://github.com/getkirby/kirby/pull/3510 x_refsource_MISC