CVE-2026-42193

Plunk: SNS webhook forgery

CVSS 9.1 CRITICALEPSS 0.1%CWE-347

Vexday Risk Score

28Low

SSVC decision (CISA)

Track

No exploitation signal → monitor

CVSS 9.1EPSS 0.1%KEV nãoPoC —Nuclei —Metasploit —Patch —

Lifecycle

08 May 2026Published on NVD

Recommendation: Monitor — no exploitation signal at the moment.

Plunk is an open-source email platform built on top of AWS SES. Prior to version 0.9.0, the /webhooks/sns endpoint accepts Amazon SNS notification payloads from unauthenticated requests without verifying the SNS signature, certificate, or topic ARN, meaning anyone can forge a valid-looking webhook request. This allows an unauthenticated attacker to spoof SNS events to trigger workflow automations, unsubscribe contacts, manipulate email delivery metrics, and potentially exhaust billing credits. This issue has been patched in version 0.9.0.

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

Affected products

useplunk · plunk

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References

https://github.com/useplunk/plunk/releases/tag/v0.9.0 https://github.com/useplunk/plunk/security/advisories/GHSA-9792-w86v-gx53