Sentry: Improper authentication on SAML SSO process allows user identity linking

### Impact A critical vulnerability was discovered in the SAML SSO implementation of Sentry. It was reported to us via our private bug bounty program. The vulnerability allows an attacker to take over any user account by using a malicious SAML Identity Provider and another organization on the same Sentry instance. The victim email address must be known in order to exploit this vulnerability. For self-hosted users, you are only vulnerable if the following conditions are met: - You have more than one organization configured (SENTRY_SINGLE_ORGANIZATION = False). - A malicious user has existing access and permissions to modify SSO settings for another organization in your multo-organization instance. ### Patches - [Sentry SaaS](https://sentry.io/): The fix was deployed on February 18, 2026. No action is required. - [Self-Hosted Sentry](https://github.com/getsentry/self-hosted): If only a single organization is allowed (SENTRY_SINGLE_ORGANIZATION = True), then no action is needed. We recommend upgrading to version 26.2.0 or higher. ### Workarounds User account-based two-factor authentication prevents an attacker from being able to complete authentication with a victim's user account. Organization administrators cannot do this on a user's behalf, this requires individual users to ensure 2FA has been enabled for their account. You can manage your two-factor authentication settings on your Account Settings > [Security](https://sentry.io/settings/account/security/) page. For step-by-step details, please see our [helpdesk article](https://sentry.zendesk.com/hc/en-us/articles/46773315774235-How-do-I-enable-two-factor-authentication-2FA-on-my-Sentry-account).

Quoted source text, attributed separately from HOL analysis.