XSS in Getkirby Kirby
CVE-2021-41258
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.
Vulnerability class: XSS (Cross-Site Scripting)
EPSS: 0.008 (53.5th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 7.3 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N.
Affected products
- Getkirby Kirby — versions >= 3.5.0, < 3.5.8
Weakness classification (CWE)
References
- security-advisories@github.com (Third Party Advisory, x_refsource_MISC, Release Notes)
- security-advisories@github.com (x_refsource_CONFIRM, Third Party Advisory)
- security-advisories@github.com (Patch, Third Party Advisory, x_refsource_MISC)
Frequently asked questions
- What is CVE-2021-41258?
- CVE-2021-41258 is a high-severity vulnerability in Getkirby Kirby, classified under Cross-site Scripting. CVSS score: 7.3/10. Published 2021-11-16.
- How severe is CVE-2021-41258?
- High severity. CVSS v3 base score is 7.3 out of 10.