MEDIUM 5.3 GitHub
CVE-2026-113799
Slack Morphism verifier errors disclose valid HMACs in the logs
### Summary
Slack Morphism exposes the correct Slack request HMAC when signature verification fails.
For an invalid request, `slack-morphism` computes the correct signature for the attacker-controlled timestamp and request body and stores it in `SlackEventWrongSignatureError.generated_hash`. The error's `Debug` and `Display` representations expose that value, and the default Axum listener error handler logs it at error level.
An attacker who can both reach the application's Slack callback end
Affected Products
- rust/slack-morphism >= 1.0.0, <= 2.27.0
References
- https://github.com/advisories/GHSA-26w4-8w32-4x3v
- https://github.com/abdolence/slack-morphism-rust/security/advisories/GHSA-26w4-8w32-4x3v
- https://github.com/abdolence/slack-morphism-rust/pull/387
- https://github.com/abdolence/slack-morphism-rust/commit/ac95d0d4539d0eac548a8db99c51c0c1ae
This medium severity vulnerability with a CVSS score of 5.3 was published on 2026-10-21 via GitHub. Affected: rust/slack-morphism >= 1.0.0, <= 2.27.0.
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