slackapi / slackapi/slack-github-action
Slack does not display attached image URLs correctly due to long JWT token in Markdown
@zimeg is already working on this.
Since Sep 10, 2025.
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Description
When an image is attached to an issue or comment in GitHub, the generated URL now includes a long JWT token. For example:
[Image](https://private-user-images.githubusercontent.com/151300/487659672-835e89e5-d1a0-452f-a924-XXXXXXXX.png?jwt=eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJpc3MiOiJnaXRodWIuY29tIiwiYXVkIjoicmF3LmdpdGh1YnVzZXJjb250ZW50LmNvbSIsImtleSI6ImtleTUiLCJleHAiOjE3NTc0O.....
When this URL is sent in a Slack message, the middle of the token is truncated, resulting in an incomplete Markdown image syntax and the image not being displayed correctly. Instead, a very long URL with a JWT token is exposed, making it difficult to view.
It appears this issue arose because GitHub changed the format of attached file URLs to include a token. Please investigate how to improve the Slack GitHub Action so that image URLs are shown correctly in Slack messages, or are transformed to display images properly without exposing the long JWT token in the message.
🙏🏼
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