GHSA-gxhx-2686-5h9g slack-go `SecretsVerifier` accepts empty signing secret without precondition
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Published
Check this codebase for GHSA-gxhx-2686-5h9g and fix it if it is affected.
What it is: GHSA-gxhx-2686-5h9g is an authentication bypass vulnerability in github.com/slack-go/slack, published on 14 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of GHSA-gxhx-2686-5h9g in the wild and no public exploit code.
Affected packages and fixed versions:
- github.com/slack-go/slack (Go): affected all versions; fixed in 0.23.1
- github.com/slack-go/slack (Go): affected all versions; fixed in 0.23.1
- github.com/slack-go/slack (Go): affected all versions; fixed in 0.23.1
Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.
Reference: https://insights.sbomify.com/GHSA-gxhx-2686-5h9g/ (Markdown: https://insights.sbomify.com/GHSA-gxhx-2686-5h9g/index.md)
An unauthenticated attacker can bypass Slack request authentication if the application is misconfigured with an empty signing secret.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is GHSA-gxhx-2686-5h9g?
GHSA-gxhx-2686-5h9g is an authentication bypass vulnerability in github.com/slack-go/slack, published on 14 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.Which versions are affected by GHSA-gxhx-2686-5h9g?
3 open source packages ship an affected version, including github.com/slack-go/slack.
| Package | Affected | Fixed in |
|---|---|---|
github.com/slack-go/slack Go | All versions | 0.23.1 |
github.com/slack-go/slack Go | All versions | 0.23.1 |
github.com/slack-go/slack Go | All versions | 0.23.1 |
How do I fix GHSA-gxhx-2686-5h9g?
Upgrade github.com/slack-go/slack to 0.23.1 or later.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is GHSA-gxhx-2686-5h9g being exploited?
There is no known exploitation of GHSA-gxhx-2686-5h9g in the wild and no public exploit code.
Sources
Also known as GO-2026-5410.