GHSA-gxhx-2686-5h9g: Github.com/slack go/slack Slack-go `SecretsVerifier` Accepts Empty Signing Vulnerability

MODERATE
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CWE-287 CWE-1391 CWE-326
Published
Advisory Summary

GHSA-gxhx-2686-5h9g is a MODERATE slack-go `secretsverifier` accepts empty signing vulnerability (CWE-287: Improper Authentication) affecting Github.com/slack go/slack libraries in the Go ecosystem. The issue involves slack-go `secretsverifier` accepts empty signing secret without precondition. Remediation is available by upgrading affected packages to version 0.23.1.

GHSA-gxhx-2686-5h9g at a Glance

CVE Identifier N/A
GHSA Identifier GHSA-gxhx-2686-5h9g
Severity MODERATE
CVSS v3.1 Base Score N/A
CWE Classification CWE-287: Improper Authentication
Affected Product Github.com/slack go/slack
Package Ecosystem Go
Published Date
Last Updated

How to Fix GHSA-gxhx-2686-5h9g

To remediate this vulnerability, upgrade all affected Github.com/slack go/slack dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

github.com/slack-go/slack fixed: 0.23.1 
Upgrade github.com/slack-go/slack to 0.23.1
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for github.com/slack-go/slack

How to Check if You Are Affected

To determine whether your application is affected by GHSA-gxhx-2686-5h9g, inspect your project dependencies for Github.com/slack go/slack:

inspect dependencies for github.com/slack-go/slack

Analyze the terminal output to locate any version of Github.com/slack go/slack in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.23.1), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-287: Improper Authentication, where when an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct. In Github.com/slack go/slack, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

`SecretsVerifier` in slack-go/slack before v0.23.1 accepts an empty signing secret without error. If an application is misconfigured (e.g., an unset or empty `SLACK_SIGNING_SECRET`), `NewSecretsVerifier` builds an HMAC-SHA256 keyed with an empty string, allowing an unauthenticated attacker to forge a valid `X-Slack-Signature` and bypass Slack request authentication. Fixed in v0.23.1, which rejects empty secrets with `ErrInvalidConfiguration`. This is patched in version 0.23.1.

GHSA-gxhx-2686-5h9g Affected Github.com/slack go/slack Versions

1 component(s)
Fixed Versions:
0.23.1
Product / Package Ecosystem Affected Versions Fixed Version
github.com/slack-go/slack
golang/github.com/slack-go/slack
Go
< 0.23.1
0.23.1

References

GitHub Advisory / Wiki ADVISORY
https://github.com/slack-go/slack/security/advisories/GHSA-gxhx-2686-5h9g
Security Fix Commit FIX COMMIT
https://github.com/slack-go/slack/commit/34ad5c052e446f58505ae8d81a2a72821de107cc
Github.com/slack go/slack Source Repository REPOSITORY
https://github.com/slack-go/slack
Github.com/slack go/slack Release RELEASE
https://github.com/slack-go/slack/releases/tag/v0.23.1

Frequently Asked Questions

What is GHSA-gxhx-2686-5h9g?
GHSA-gxhx-2686-5h9g is a security vulnerability in Github.com/slack go/slack involving slack-go `SecretsVerifier` accepts empty signing secret without precondition under CWE-287: Improper Authentication.
Which Github.com/slack go/slack versions are affected?
Affected versions include releases prior to 0.23.1 across affected packages: github.com/slack-go/slack.
What version fixes GHSA-gxhx-2686-5h9g?
Upgrading to 0.23.1 (or the latest patched release for your respective branch) resolves the vulnerability.
Is github.com/slack-go/slack affected?
Yes, github.com/slack-go/slack is affected in releases prior to 0.23.1. Upgrade your dependency to 0.23.1 or later.
What CWE is associated with GHSA-gxhx-2686-5h9g?
GHSA-gxhx-2686-5h9g is classified under CWE-287: Improper Authentication (When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.).
How can I check Go dependencies for GHSA-gxhx-2686-5h9g?
Run the dependency tree command: 'inspect dependencies for github.com/slack-go/slack'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-gxhx-2686-5h9g",
  "modified" : "2026-06-29T15:38:00Z",
  "published" : "2026-05-14T20:52:55Z",
  "aliases" : [ ],
  "summary" : "slack-go `SecretsVerifier` accepts empty signing secret without precondition",
  "details" : "`SecretsVerifier` in slack-go/slack before v0.23.1 accepts an empty signing secret without error. If an application is misconfigured (e.g., an unset or empty `SLACK_SIGNING_SECRET`), `NewSecretsVerifier` builds an HMAC-SHA256 keyed with an empty string, allowing an unauthenticated attacker to forge a valid `X-Slack-Signature` and bypass Slack request authentication. Fixed in v0.23.1, which rejects empty secrets with `ErrInvalidConfiguration`. This is patched in version 0.23.1.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N/E:U"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/slack-go/slack"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.23.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/slack-go/slack/security/advisories/GHSA-gxhx-2686-5h9g"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/slack-go/slack/commit/34ad5c052e446f58505ae8d81a2a72821de107cc"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/slack-go/slack"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/slack-go/slack/releases/tag/v0.23.1"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1391", "CWE-287", "CWE-326" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-05-14T20:52:55Z",
    "nvd_published_at" : null
  }
}