Heym before 0.0.53 Slack Webhook Signature Verification Bypass

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

Heym before 0.0.53 fails to verify Slack request signatures when trigger nodes lack credential IDs or have empty signing secrets. Remote unauthenticated attackers can send forged Slack events to known webhook URLs to trigger workflows with the owner's credentials.

Source published

27 Sep 2026 16:28:28 UTC

Source modified

28 Sep 2026 14:18:44 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: cve-program · CVE Program Terms of Use. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 4.0 · 8.3 CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N

CVSS 3.1 · 6.5 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N