CVE-2026-34821 Endian Firewall /manage/vpnauthentication/user/ remark Stored Cross-Site Scripting
An authenticated attacker can inject malicious JavaScript into the VPN user remark field, leading to script execution in other users' browsers.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-34821?
CVE-2026-34821 is a medium-severity cross-site scripting vulnerability in Endian Firewall, published on 2 Apr 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official description
Endian Firewall version 3.3.25 and prior allow stored cross-site scripting (XSS) via the remark parameter to /manage/vpnauthentication/user/. An authenticated attacker can inject arbitrary JavaScript that is stored and executed when other users view the affected page.
Weakness: CWE-79
Which versions are affected by CVE-2026-34821?
It affects 1 product.
Products include Endian Firewall Community.
How do I fix CVE-2026-34821?
No fix has been published for CVE-2026-34821 yet. Limit exposure of the affected software until one is available.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-34821 being exploited?
There is no known exploitation of CVE-2026-34821 in the wild and no public exploit code.
Other vulnerabilities in Endian Firewall
- CVE-2021-27201 Command injection in n/a
- CVE-2026-34791 Endian Firewall /cgi-bin/logs_proxy.cgi DATE Perl Command Injection
- CVE-2026-34792 Endian Firewall /cgi-bin/logs_clamav.cgi DATE Perl Command Injection
- CVE-2026-34793 Endian Firewall /cgi-bin/logs_firewall.cgi DATE Perl Command Injection
- CVE-2026-34794 Endian Firewall /cgi-bin/logs_ids.cgi DATE Perl Command Injection
Sources
Also known as GHSA-qxfx-cg86-j76f.