CVE-2026-42193
Unauthenticated SNS Webhook Spoofing in Plunk
Publication date: 2026-05-08
Last updated on: 2026-05-08
Assigner: GitHub, Inc.
Description
Description
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| plunk | plunk | to 0.9.0 (exc) |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-347 | The product does not verify, or incorrectly verifies, the cryptographic signature for data. |
Attack-Flow Graph
AI Powered Q&A
How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:
The vulnerability allows unauthenticated attackers to spoof SNS events, which can lead to manipulation of email delivery metrics, unauthorized workflow automation triggers, and unsubscribing contacts without consent.
Such unauthorized actions could potentially result in non-compliance with regulations like GDPR and HIPAA, which require protection of personal data and user consent for communications.
Specifically, the ability to unsubscribe contacts or manipulate email workflows without proper authentication may violate user consent requirements and data integrity principles mandated by these standards.
Can you explain this vulnerability to me?
This vulnerability exists in Plunk, an open-source email platform using AWS SES, in versions prior to 0.9.0. The /webhooks/sns endpoint accepts Amazon SNS notification payloads without verifying the SNS signature, certificate, or topic ARN. This means that anyone can send forged webhook requests that appear valid.
Because of this lack of verification, an unauthenticated attacker can spoof SNS events to trigger workflow automations, unsubscribe contacts, manipulate email delivery metrics, and potentially exhaust billing credits.
This issue was fixed in version 0.9.0 by adding proper verification of SNS requests.
How can this vulnerability impact me? :
The vulnerability allows an attacker to spoof SNS events, which can have several impacts:
- Trigger unauthorized workflow automations.
- Unsubscribe contacts without permission.
- Manipulate email delivery metrics, potentially affecting reporting and decision-making.
- Exhaust billing credits by triggering excessive or fraudulent usage.
What immediate steps should I take to mitigate this vulnerability?
To mitigate this vulnerability, upgrade Plunk to version 0.9.0 or later, where the /webhooks/sns endpoint properly verifies Amazon SNS notification payloads by checking the SNS signature, certificate, and topic ARN.