EUVD-2026-19359CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N
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Description
Plunk is an open-source email platform built on top of AWS SES. Prior to 0.8.0, a CRLF header injection vulnerability was discovered in SESService.ts, where user-supplied values for from.name, subject, custom header keys/values, and attachment filenames were interpolated directly into raw MIME messages without sanitization. An authenticated API user could inject arbitrary email headers (e.g. Bcc, Reply-To) by embedding carriage return/line feed characters in these fields, enabling silent email forwarding, reply redirection, or sender spoofing. The fix adds input validation at the schema level to reject any of these fields containing \r or \n characters, consistent with the existing validation already applied to the contentId field. This vulnerability is fixed in 0.8.0.
Analysis
CRLF injection in Plunk email platform's SESService.ts allows authenticated API users to inject arbitrary MIME headers by embedding carriage return/line feed sequences in user-controlled fields (from.name, subject, custom headers, attachment filenames). Attackers can silently add Bcc headers for email forwarding, manipulate Reply-To addresses, or spoof senders by exploiting the lack of input sanitization before MIME message construction. …
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Remediation
Within 24 hours: Identify all Plunk deployments and current version numbers in your infrastructure; notify relevant teams of authentication restrictions as interim control. Within 7 days: Upgrade all Plunk instances to version 0.8.0 or later; validate deployment and test email header handling post-patch. …
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