CVE-2026-28355
Received Received - Intake
Self-XSS Vulnerability in Canarytokens PWA Installation Page

Publication date: 2026-02-27

Last updated on: 2026-02-27

Assigner: GitHub, Inc.

Description
Canarytokens help track activity and actions on a network. Versions prior to `sha-7ff0e12` have a Self Cross-Site Scripting vulnerability in the "PWA" Canarytoken, whereby the Canarytoken's creator can attack themselves or someone they share the link with. The creator of a PWA Canarytoken can insert Javascript into the title field of their PWA token. When the creator later browses the installation page for their own Canarytoken, the Javascript executes. This is a self-XSS. An attacker could create a Canarytoken with this self-XSS, and send the install link to a victim. When they click on it, the Javascript would execute. However, no sensitive information (ex. session information) will be disclosed to the malicious actor. This issue is now patched on Canarytokens.org. Users of self-hosted Canarytokens installations can update by pulling the latest Docker image, or any Docker image after sha-7ff0e12.
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Meta Information
Published
2026-02-27
Last Modified
2026-02-27
Generated
2026-06-16
AI Q&A
2026-02-27
EPSS Evaluated
2026-06-14
NVD
CVE-2026-28355
EUVD
EUVD-2026-9072
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
thinkst canarytokens to sha-7ff0e12 (exc)
Helpful Resources
Exploitability
CWE
CWE Icon
KEV
KEV Icon
CWE ID Description
CWE-79 The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.
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Executive Summary

[{'type': 'paragraph', 'content': 'CVE-2026-28355 is a Stored Self Cross-Site Scripting (Self-XSS) vulnerability in the "PWA" Canarytoken component of the Canarytokens project. The vulnerability arises because the title field of a PWA Canarytoken allows the token creator to insert arbitrary JavaScript code. When the creator later visits the installation page of their own Canarytoken, the injected JavaScript executes in their browser context.'}, {'type': 'paragraph', 'content': 'An attacker can craft a Canarytoken containing malicious JavaScript and send the installation link to a victim, causing the script to execute when the victim opens the link. However, no sensitive information such as session data is disclosed to the attacker.'}, {'type': 'paragraph', 'content': 'This vulnerability is classified under CWE-79 due to improper sanitization of user input before rendering it in a web page. It affects versions prior to commit sha-7ff0e12 and has been patched in that commit.'}] [1]

Impact Analysis

[{'type': 'paragraph', 'content': 'This vulnerability allows the creator of a PWA Canarytoken to execute arbitrary JavaScript code in their own browser when viewing the installation page, which is a self-XSS scenario.'}, {'type': 'paragraph', 'content': "Additionally, an attacker could send a malicious Canarytoken installation link to a victim, causing the injected JavaScript to execute in the victim's browser when they open the link."}, {'type': 'paragraph', 'content': 'Despite this, the impact is limited because no sensitive information such as session data is disclosed to the attacker, and the overall severity is rated low.'}] [1]

Compliance Impact

I don't know

Detection Guidance

This vulnerability is a Stored Self Cross-Site Scripting (Self-XSS) in the title field of the PWA Canarytoken. Detection involves identifying Canarytokens with injected JavaScript in the title field.

Since the vulnerability manifests when the token creator visits the installation page, monitoring for unusual JavaScript execution in the browser context of the token creator can help detect exploitation.

For self-hosted installations, you can check the version of your Canarytokens Docker image to see if it is prior to the patched commit sha-7ff0e12.

  • Run the command to check your current Docker image version: `docker images thinkst/canarytokens`
  • Look for any Canarytoken PWA titles containing suspicious JavaScript code by inspecting the token creation inputs or stored token data.
Mitigation Strategies

To mitigate this vulnerability, update your Canarytokens installation to a version that includes the patch after commit sha-7ff0e12.

For self-hosted Canarytokens installations, pull the latest Docker image with the following command:

  • `docker pull thinkst/canarytokens:latest`

Avoid creating or sharing Canarytokens with untrusted JavaScript in the title field to prevent self-XSS attacks.

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