Summary

Summary

Upon browsing the https://www.impresscms.org/, one of the post include the public Slack Channel however the devel channel exposed some of the private h1 reports.

Checking ImpressCMS hacktivity the issues that get resolved/reported are private which helps me to verify that the team doesn't want to expose these issues that reported on Hackerone.

Steps To Reproduce

• Go to https://www.impresscms.org/modules/news/article.php?article_id=1019
• Signup a Slack account
• After successful installation, go to devel channel
• Scroll up to top and you can disclose different reports from h1.

Possible Mitigation

Convert those channel that contain sensitive information to private channels. https://www.businessinsider.com/how-to-make-a-slack-channel-private Impact

This allows the attacker to read old exploit and those exploit can be use for outdated version of ImpressCMS