abdolence slack-morphism-rust up to 2.27.0 Signature Verification information disclosure

Summaryinfo

A vulnerability was found in abdolence slack-morphism-rust up to 2.27.0. It has been classified as problematic. This affects an unknown part of the component Signature Verification. The manipulation leads to information disclosure. This vulnerability is uniquely identified as CVE-2026-113799. The attack is possible to be carried out remotely. No exploit exists. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability was found in abdolence slack-morphism-rust up to 2.27.0 and classified as problematic. This issue affects an unknown code block of the component Signature Verification. The manipulation with an unknown input leads to a information disclosure vulnerability. Using CWE to declare the problem leads to CWE-200. The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. Impacted is confidentiality. The summary by CVE is:

Slack Morphism is a client library for Slack Web/Events API/Socket Mode and Block Kit. Versions 1.0.0 through 2.27.0 expose 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 endpoint and read its application/service logs can therefore use the verifier as a chosen-message HMAC oracle. The attacker can send an arbitrary request with an invalid signature, recover the correct signature from the resulting log entry, and resend the same request within the five-minute freshness window. The second request passes Slack Morphism's signature verification and reaches the protected application callback without the attacker knowing the Slack signing secret. Version 2.28.0 patches the issue.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-113799 since 10/20/2026. The exploitation is known to be easy. The attack may be initiated remotely. Neither technical details nor an exploit are publicly available. MITRE ATT&CK project uses the attack technique T1592 for this issue.

Upgrading to version 2.28.0 eliminates this vulnerability.

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Productinfo

Type

• Messaging Software

Vendor

• abdolence

Name

• slack-morphism-rust

Version

• 2.0
• 2.1
• 2.2
• 2.3
• 2.4
• 2.5
• 2.6
• 2.7
• 2.8
• 2.9
• 2.10
• 2.11
• 2.12
• 2.13
• 2.14
• 2.15
• 2.16
• 2.17
• 2.18
• 2.19
• 2.20
• 2.21
• 2.22
• 2.23
• 2.24
• 2.25
• 2.26
• 2.27.0

Website

• Product: https://github.com/abdolence/slack-morphism-rust/

CPE 2.3info

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CPE 2.2info

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