Vulnerability · Published May 29, 2026 · Assigned by GitHub_M

CVE-2026-47123FreeScout: Agent Impersonation via Missing HMAC Verification on Notification Reply Message-ID Path

High 7.5

In plain English

A high-severity authentication bypass by spoofing in freescout from freescout-help-desk. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 4% of all known vulnerabilities).

Severity (CVSS 3.1)7.5High

Exploit odds (30 days)0.1%top 96.2% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official description

FreeScout is a free help desk and shared inbox built with PHP's Laravel framework. Prior to 1.8.220, the email processing pipeline in FreeScout's FetchEmails command has two code paths for identifying agent (user) replies based on In-Reply-To / References headers. The notification reply path (notify-{thread_id}-{user_id}-...) extracts thread_id and user_id directly from the Message-ID without HMAC verification. An external attacker who can spoof the From address of a helpdesk agent can inject messages that FreeScout processes as legitimate agent replies — which are then automatically forwarded to customers via the legitimate SMTP server. This vulnerability is fixed in 1.8.220.

Affected products (as reported)

Vendor	Product	Versions
freescout-help-desk	freescout	< 1.8.220

Weakness: CWE-290, CWE-345 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:H/A:N