CVE-2025-32378: Shopware Auth Bypass Vulnerability

CVE-2025-32378 Overview

CVE-2025-32378 is a business logic flaw in Shopware, an open source e-commerce platform. The default configuration of the double-opt-in mechanism allows anyone to register a newsletter subscription against an arbitrary email address without confirmation. Attackers can weaponize this to send unsolicited newsletter emails at scale, effectively turning the shop into a mailer for spam or harassment campaigns. The issue is fixed in Shopware 6.6.10.3 and 6.5.8.17. The weakness is categorized as [CWE-799] Improper Control of Interaction Frequency.

Critical Impact
Unauthenticated attackers can trigger mass newsletter confirmation emails to arbitrary recipients, damaging sender reputation and enabling email-based harassment or spam amplification.

Affected Products

Shopware versions prior to 6.5.8.17 (6.5.x branch)
Shopware versions prior to 6.6.10.3 (6.6.x branch)
Shopware 6.7.0.0-rc1

Discovery Timeline

2025-04-09 - CVE-2025-32378 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-32378

Vulnerability Analysis

The flaw resides in Shopware's default handling of newsletter double-opt-in for registered customers. Shopware ships with Newsletter: Double Opt-in enabled, but Newsletter: Double opt-in for registered customers and Log-in & sign-up: Double opt-in on sign-up both disabled. Under this configuration, any visitor can register a shop account using an arbitrary email address and then toggle the newsletter checkbox on the account page. The platform treats the sign-up as trusted because the account was created, and marks the recipient as "instantly active" in the backend. No confirmation link is ever validated. The recipient receives two emails — a registration confirmation and a newsletter subscription confirmation — without any action on their part.

Root Cause

The root cause is an insecure default configuration combined with a business logic gap. The double-opt-in policy for anonymous newsletter sign-ups is not enforced when a subscription is initiated from within a newly created customer account. The account creation flow itself does not require email verification, so registration cannot substitute for opt-in confirmation. The subscription state transitions directly to active without an intermediate confirmation step.

Attack Vector

Exploitation is remote, unauthenticated, and requires no user interaction from the victim. An attacker scripts account creation against the storefront using a target email address, then submits the newsletter opt-in from the account settings. Repeating this across many target addresses generates high volumes of confirmation email from the shop's mail infrastructure. Because the shop domain is the sender, this abuses its sender reputation and can be used to flood inboxes or bypass reputation-based spam filters. See the Shopware GitHub Security Advisory GHSA-4h9w-7vfp-px8m for vendor details.

Detection Methods for CVE-2025-32378

Indicators of Compromise

Unusual spikes in customer account registrations followed immediately by newsletter subscription events from the same session or IP range.
Newsletter recipients in the admin backend marked as "instantly active" without a corresponding confirmation event in mail logs.
Outbound SMTP volume increases from the Shopware mail queue targeting unrelated third-party domains.

Detection Strategies

Query the Shopware database for newsletter_recipient rows where status = 'optIn' but no confirmedAt timestamp exists or the confirmation IP matches the registration IP.
Correlate storefront /account/register POST requests with subsequent /account/newsletter POST requests from the same client within short time windows.
Baseline newsletter sign-up rates per hour and alert on statistical deviations that align with automated abuse patterns.

Monitoring Recommendations

Enable web server access logging with client IP, user agent, and session identifier retention for storefront account and newsletter endpoints.
Forward Shopware application and mail transport logs to a centralized log platform for correlation and long-term retention.
Monitor mail server bounce rates and abuse complaint feedback loops from major providers for reputational drift.

How to Mitigate CVE-2025-32378

Immediate Actions Required

Upgrade Shopware to 6.6.10.3 or 6.5.8.17 or later, which enforce double-opt-in for the affected registration path.
Enable Newsletter: Double opt-in for registered customers and Log-in & sign-up: Double opt-in on sign-up in the shop administration until patches are applied.
Audit newsletter_recipient records created before patching and revoke subscriptions that lack a valid confirmation trail.

Patch Information

Shopware fixed the vulnerability in versions 6.6.10.3 and 6.5.8.17. Operators running the 6.7.0.0-rc1 release candidate should move to a fixed stable release. Patch details are published in the Shopware GitHub Security Advisory GHSA-4h9w-7vfp-px8m.

Workarounds

Set both Newsletter: Double opt-in for registered customers and Log-in & sign-up: Double opt-in on sign-up to active in the storefront settings.
Add rate limiting and CAPTCHA to the customer registration and newsletter subscription endpoints at the web server or WAF layer.
Restrict newsletter opt-in to email addresses that match the authenticated account email and have completed a separate verification challenge.

bash

# Configuration example - enforce full double-opt-in in Shopware admin
# Settings > Shop > Login / Registration
#   core.loginRegistration.doubleOptInRegistration = true
#   core.loginRegistration.doubleOptInEmailValidation = true
# Settings > Shop > Newsletter
#   core.newsletter.doubleOptIn = true
#   core.newsletter.doubleOptInRegistered = true