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Vulnerability record · CVE-2026-42193 · published 8 May 2026

CVE-2026-42193: Improper verification of cryptographic signature vulnerability

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.

9.1 CVSS 3.1 Critical EPSS 0.21% · top 90.6% CWE-347 · Improper verification of cryptographic signature Deferred
9.1CVSS 3.1 base score
0.21%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
2References
17 Jun 2026Last modified by NVD

Description

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

References

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

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Source: NIST National Vulnerability Database (record CVE-2026-42193), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.