CVE-2026-42193: CWE-347: Improper Verification of Cryptographic Signature in useplunk plunk
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.
AI Analysis
Technical Summary
Plunk versions before 0.9.0 contain a vulnerability (CWE-347) where the /webhooks/sns endpoint accepts Amazon SNS notification payloads without verifying the cryptographic signature, certificate, or topic ARN. This improper verification allows unauthenticated attackers to forge SNS webhook requests that appear valid. Exploitation can result in unauthorized triggering of email platform workflows, manipulation of email delivery data, and potential financial impact through billing credit exhaustion. The vulnerability is fixed in version 0.9.0. Since plunk is a cloud service, the vendor typically manages patching and remediation server-side.
Potential Impact
An attacker can spoof SNS webhook requests to the plunk platform, leading to unauthorized workflow automation triggers, contact unsubscriptions, manipulation of email delivery metrics, and potential exhaustion of billing credits. This compromises the integrity of email operations and may cause financial loss. There is no indication of direct data confidentiality impact. No known exploits are reported in the wild at this time.
Mitigation Recommendations
A patch addressing this vulnerability is available in plunk version 0.9.0. Users should upgrade to version 0.9.0 or later to ensure proper verification of SNS webhook requests. Since plunk is a cloud-hosted service, the vendor manages remediation for this service; users should verify with the vendor that their instance is updated. Patch status is confirmed as available. No additional mitigation steps are specified by the vendor.
CVE-2026-42193: CWE-347: Improper Verification of Cryptographic Signature in useplunk plunk
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 v3.1
Score 9.1critical
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
Plunk versions before 0.9.0 contain a vulnerability (CWE-347) where the /webhooks/sns endpoint accepts Amazon SNS notification payloads without verifying the cryptographic signature, certificate, or topic ARN. This improper verification allows unauthenticated attackers to forge SNS webhook requests that appear valid. Exploitation can result in unauthorized triggering of email platform workflows, manipulation of email delivery data, and potential financial impact through billing credit exhaustion. The vulnerability is fixed in version 0.9.0. Since plunk is a cloud service, the vendor typically manages patching and remediation server-side.
Potential Impact
An attacker can spoof SNS webhook requests to the plunk platform, leading to unauthorized workflow automation triggers, contact unsubscriptions, manipulation of email delivery metrics, and potential exhaustion of billing credits. This compromises the integrity of email operations and may cause financial loss. There is no indication of direct data confidentiality impact. No known exploits are reported in the wild at this time.
Mitigation Recommendations
A patch addressing this vulnerability is available in plunk version 0.9.0. Users should upgrade to version 0.9.0 or later to ensure proper verification of SNS webhook requests. Since plunk is a cloud-hosted service, the vendor manages remediation for this service; users should verify with the vendor that their instance is updated. Patch status is confirmed as available. No additional mitigation steps are specified by the vendor.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-04-25T01:53:21.584Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
- Is Cloud Service
- true
Threat ID: 69fe575bcbff5d86102f6112
Added to database: 05/08/2026, 21:36:27 UTC
Last enriched: 05/16/2026, 10:50:58 UTC
Last updated: 06/29/2026, 13:09:16 UTC
Views: 110
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