Answer in brief
CVE-2026-113799 records a Medium severity (CVSS 5.3) vulnerability in Slack Morphism verifier errors disclose valid HMACs in the logs. The current sources do not mark it as known exploited. The current feed maps slack-morphism (crates.io), abdolence/slack-morphism-rust (generic), slack-morphism (rust). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 5.3. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps slack-morphism (crates.io), abdolence/slack-morphism-rust (generic), slack-morphism (rust). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| slack-morphismcrates.io | >=1.0.0 <2.28.0 | 2.28.0 |
| abdolence/slack-morphism-rustgeneric | >=1.0.0 <2.28.0 | 2.28.0 |
| slack-morphismrust | >=1.0.0,<=2.27.0 | 2.28.0 |
Published upstream
Oct 21, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 21, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Oct 21, 2026
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.
Quoted source text, attributed separately from HOL analysis.