Element Web and Element Desktop before 1.12.32 Forced Logout via Guest Credential URL Parameters

Summary

Element Web and Element Desktop before 1.12.32 accept guest credentials from URL fragment parameters in loadSession, allowing remote unauthenticated attackers to log out users and clear local stores. Attackers can lure logged-in users into opening links with guest_user_id and guest_access_token to force an attacker-controlled guest session and destroy unbacked end-to-end encryption keys.

Remediation

1. Inventory every element-hq element-web deployment, including staging.
2. Upgrade element-hq element-web to 1.12.32.
3. Confirm the running version after the upgrade.

References

• Patchhttps://github.com/element-hq/element-web/commit/792453c88a399d570599f5d73b08b40157cd80c0
• Advisoryhttps://abraxaslabs.tech/research/element-fragment-guest
• Advisoryhttps://github.com/element-hq/element-web/security/advisories/GHSA-c88w-7h6p-27xr
• Advisoryhttps://www.vulncheck.com/advisories/element-web-and-element-desktop-before-1.12.32-forced-logout-via-guest-credential-url-parameters
• Referencehttps://github.com/element-hq/element-web
• Referencehttps://github.com/element-hq/element-web/blob/v1.12.31/apps/web/src/Lifecycle.ts#L188
• Referencehttps://github.com/element-hq/element-web/releases/tag/v1.12.32