CVE-2026-47123 FreeScout: Agent Impersonation via Missing HMAC Verification on Notification Reply Message-ID Path
Attackers can impersonate agents by spoofing email headers due to missing HMAC verification, injecting messages forwarded to customers.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-47123?
CVE-2026-47123 is a high-severity authentication bypass vulnerability in freescout-help-desk freescout, published on 29 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
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.
Which versions are affected by CVE-2026-47123?
How do I fix CVE-2026-47123?
No fix has been published for CVE-2026-47123 yet. Limit exposure of the affected software until one is available.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-47123 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-47123 exists.
Sources
Also known as GHSA-6r38-6mcf-2ww3.