Quick answers
- Is CVE-2026-35390 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-35390 being exploited in the wild.
- How severe is CVE-2026-35390?
- Medium severity, with a CVSS score of 5.4, published 6 April 2026.
- Which products and versions are affected?
- Bulwark Webmail < 1.4.11.
- Is there a fix for CVE-2026-35390?
- A patch was published on 2026-04-06: Fix released in version 1.4.11 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-35390 attacked?
- It is attacked over the network, in a web application.
- Am I affected by CVE-2026-35390?
- Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
A vulnerability exists in Bulwark Webmail's reverse proxy (proxy.ts) where the Content-Security-Policy-Report-Only header was used instead of the enforcing Content-Security-Policy header. This misconfiguration effectively disabled CSP protections, allowing Cross-Site Scripting (XSS) attacks to proceed unblocked. An attacker can exploit this by sending a crafted HTML email containing malicious scripts. If a user views the email, the script executes in the context of the webmail application, enabling session token theft or unauthorized state-changing actions. The issue is resolved in version 1.4.11 by switching to an enforcing CSP header.
Affected products
- Bulwark Webmail < 1.4.11
Timeline
- 2026-04-02: advisory: GitHub Security Advisory published
- 2026-04-06: disclosed: CVE published to NVD
- 2026-04-06: patched: Fix released in version 1.4.11