What’s Vulnerable › Vulnerabilities

CVE-2026-42193: Plunk: SNS webhook forgery

• Severity: critical (CVSS 9.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-05-08 · updated 2026-10-26
• Weakness: CWE-347

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.

Affected products

• useplunk plunk: before 0.9.0

References

• 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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