# CVE-2026-12888: Thinkst Canarytokens HTML injection in Google Chat notifications

Source: https://junglewise.ai/threats/cve-2026-12888-thinkst-canarytokens-html-injection-in-google-chat-notifications  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-22. Updated: 2026-06-22  
License: CC BY 4.0 with a link back

CVE-2026-12888 · Severity: info · CVSS 0 · Published 2026-06-22

Thinkst Canarytokens is a tool used to create 'honeytokens' that alert security teams when an intruder interacts with them. A vulnerability in the Google Chat notification system allowed attackers to inject custom HTML content, such as links and images, into the alerts sent to security teams. While this does not allow for full system takeover, it could be used to mislead security responders or conduct phishing attacks within the internal chat environment.

Technologies: [Thinkst Applied Research Canarytokens](https://junglewise.ai/threats/technologies/canarytokens). Vendors: [Thinkst Applied Research](https://junglewise.ai/threats/vendors/thinkst-applied-research).

## Quick answers

**Is CVE-2026-12888 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-12888 being exploited in the wild.

**How severe is CVE-2026-12888?** Informational severity, with a CVSS score of 0, published 22 June 2026.

**Which products and versions are affected?** Thinkst Applied Research Canarytokens Docker tag sha-4aef1db90 before sha-8ab4dccd; Git commit 4aef1db90 before 8ab4dccd.

**Is there a fix for CVE-2026-12888?** A patch was published on 2026-06-22. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-12888 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-12888?** Check whether you run Thinkst Applied Research Canarytokens 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.

## Technical details

An HTML injection vulnerability exists in the Google Chat notification component of Thinkst Canarytokens. The root cause is the failure to escape certain fields, specifically the User-Agent and Referer headers, before they are transmitted via the Google Chat webhook. A remote, unauthenticated attacker can trigger a canarytoken with malicious header values to inject limited HTML elements, such as links and images, into the resulting Google Chat notification. This allows for interface manipulation and potential phishing within the chat session. The issue is patched in Docker images and Git commits following sha-8ab4dccd.

## Affected products

- Thinkst Applied Research Canarytokens Docker tag sha-4aef1db90 before sha-8ab4dccd; Git commit 4aef1db90 before 8ab4dccd

## Timeline

- 2026-06-22: disclosed
- 2026-06-22: advisory
- 2026-06-22: patched

## References

- [https://github.com/thinkst/canarytokens/security/advisories/GHSA-vcfc-7466-8q65](https://github.com/thinkst/canarytokens/security/advisories/GHSA-vcfc-7466-8q65)

## Related threats

- [Thinkst Canarytokens stored XSS in AWS API key store](https://junglewise.ai/threats/cve-2026-13140-thinkst-canarytokens-stored-xss-in-aws-api-key-store)
- [Thinkst Canarytokens HTML injection in fetch links email](https://junglewise.ai/threats/cve-2026-11859-thinkst-canarytokens-html-injection-in-fetch-links-email)
- [Thinkst Canarytokens HTML injection in notification emails](https://junglewise.ai/threats/cve-2026-10729-thinkst-canarytokens-html-injection-in-notification-emails)