# CVE-2026-49276: Kirby CMS self-XSS in writer field

Source: https://junglewise.ai/threats/cve-2026-49276-kirby-cms-self-xss-in-writer-field  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-09. Updated: 2026-07-09  
License: CC BY 4.0 with a link back

CVE-2026-49276 · Severity: high · CVSS 4 · Published 2026-07-09

Kirby CMS, a platform used for building and managing websites, contains a security flaw in its 'writer' field component. An attacker could potentially trick a site administrator into clicking a malicious link within the management panel, leading to the execution of unauthorized scripts. While primarily a 'self-XSS' issue requiring user interaction, it could lead to unauthorized actions being performed within the administrative interface.

Technologies: [Kirby](https://junglewise.ai/threats/technologies/kirby), [getkirby/cms (Packagist)](https://junglewise.ai/threats/technologies/getkirby-cms). Vendors: [Kirby](https://junglewise.ai/threats/vendors/kirby), [Packagist](https://junglewise.ai/threats/vendors/packagist).

## Quick answers

**Is CVE-2026-49276 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-49276 being exploited in the wild.

**How severe is CVE-2026-49276?** High severity, with a CVSS score of 4, published 9 July 2026.

**Which products and versions are affected?** Kirby < 4.9.4, >= 5.0.0, < 5.4.4, <= 4.9.3, >= 5.0.0-alpha.1, <= 5.4.3; getkirby/cms (Packagist) ECOSYSTEM:introduced=0,fixed=4.9.4.

**Is there a fix for CVE-2026-49276?** Yes. getkirby/cms (Packagist): upgrade to 4.9.4 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-49276 attacked?** It is attacked over the network, in a web application.

**Am I affected by CVE-2026-49276?** Check whether you run Kirby or getkirby/cms (Packagist) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- getkirby/cms (Packagist): upgrade to 4.9.4 or later

  ```sh
  composer require getkirby/cms:^4.9.4
  ```


## Technical details

A self-cross-site scripting (XSS) vulnerability exists in the Kirby CMS 'writer' field and the underlying <k-writer> component. The vulnerability stems from improper neutralization of scripting links (e.g., javascript: URIs) used as targets for link or email components. While the backend typically sanitizes these values before storage, a user can trigger the execution of the script by clicking the link within the Panel interface before the content is saved. Exploitation requires social engineering to convince a Panel user to enter and then click the malicious link, or knowledge of the content structure to facilitate the attack. The issue is fixed in versions 4.9.4 and 5.4.4 by implementing more robust validation against dangerous URL schemes.

## Affected products

- getkirby Kirby CMS < 4.9.4, >= 5.0.0, < 5.4.4

## Identifiers

- CVE-2026-49276
- GHSA-rhj6-r49h-5932

## Timeline

- 2026-06-17: patched: Versions 4.9.4 and 5.4.4 released
- 2026-07-09: disclosed: CVE-2026-49276 published

## References

- [https://github.com/getkirby/kirby/releases/tag/4.9.4](https://github.com/getkirby/kirby/releases/tag/4.9.4)
- [https://github.com/getkirby/kirby/releases/tag/5.4.4](https://github.com/getkirby/kirby/releases/tag/5.4.4)
- [https://github.com/getkirby/kirby/security/advisories/GHSA-rhj6-r49h-5932](https://github.com/getkirby/kirby/security/advisories/GHSA-rhj6-r49h-5932)

## Related threats

- [Kirby path traversal in media handler via encoded slashes](https://junglewise.ai/threats/cve-2026-75594-kirby-path-traversal-in-media-handler-via-encoded-slashes)
- [Kirby path traversal in media handling via sibling directory bypass](https://junglewise.ai/threats/cve-2026-75592-kirby-path-traversal-in-media-handling-via-sibling-directory)
- [Kirby authorization bypass in REST API file uploads](https://junglewise.ai/threats/cve-2026-71415-kirby-authorization-bypass-in-rest-api-file-uploads)
- [Kirby REST API information disclosure via error messages](https://junglewise.ai/threats/cve-2026-69127-kirby-rest-api-information-disclosure-via-error-messages)
- [Kirby CMS stored XSS via dangerous URL schemes in KirbyTags](https://junglewise.ai/threats/cve-2026-45368-kirby-cms-stored-xss-via-dangerous-url-schemes-in-kirbytags)