CVE-2026-42193Network attack vector

Unauthenticated SNS event forgery via unsigned webhooks

Published May 8, 2026 · Updated May 8, 2026

Improper signature verification in Plunk before 0.9.0 allows remote attackers to forge Amazon SNS webhook events without authentication. The /webhooks/sns handler trusts notification bodies without validating the SNS signature, signing certificate, or permitted topic ARN. Network access to the endpoint is sufficient to trigger workflows, unsubscribe contacts, corrupt delivery metrics, or consume billing credits.

CVSS severity9.1
Critical
EPSS probability0.13%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Improper signature verification in Plunk before 0.9.0 allows remote attackers to forge Amazon SNS webhook events without authentication. The /webhooks/sns handler trusts notification bodies without validating the SNS signature, signing certificate, or permitted topic ARN. Network access to the endpoint is sufficient to trigger workflows, unsubscribe contacts, corrupt delivery metrics, or consume billing credits.

The record

CVE
CVE-2026-42193
Published
May 8, 2026
Updated
May 8, 2026
Vendor
Plunk
Product
Plunk
Classifications
CWE-347, T1565.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 8, 2026CVE publishedPublication date reported by the CVE source.
  2. May 8, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 0.9.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Plunk · Plunkversion=< 0.9.0

Published CVSS scores

9.1GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-347Improper Verification of Cryptographic Signature
T1565.001Stored Data Manipulation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo