CVE-2026-55666 Rocket.Chat: Email Parameter Fallback Leads To Account Takeover Within Apple OAuth
Attackers can take over accounts by forging Apple OAuth tokens that omit the email field, causing the application to accept an attacker-supplied email address.
- 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-2026-55666?
CVE-2026-55666 is a critical authentication bypass vulnerability in RocketChat Rocket.Chat, published on 24 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Rocket.Chat is an open-source, secure, fully customizable communications platform. Prior to 8.5.1, 8.4.4, 8.3.6, 8.2.6, 8.1.6, 8.0.7, and 7.10.13, in apps/meteor/app/apple/server/loginHandler.ts, handleIdentityToken parses a JWT issued by Apple during the OAuth flow. The try block checks for an email parameter. If the JWT does not contain an email address, the application falls back to accepting an arbitrary email value supplied directly in the request. Attackers are able to forge Apple JWTs that do not contain an email address and leverage this vulnerability to carry out account takeover attacks. This vulnerability is fixed in 8.5.1, 8.4.4, 8.3.6, 8.2.6, 8.1.6, 8.0.7, and 7.10.13.
Which versions are affected by CVE-2026-55666?
How do I fix CVE-2026-55666?
No fix has been published for CVE-2026-55666 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-2026-55666 being exploited?
There is no known exploitation of CVE-2026-55666 in the wild and no public exploit code.
Sources
Also known as GHSA-wx3c-76rf-wpwf.