Vulnerability · Published May 11, 2026 · Assigned by GitHub_M

CVE-2026-44659Zen Browser Mac - Address Bar Spoofing via Long Subdomain

Medium 4.7

In plain English

A medium-severity security flaw in desktop from zen-browser. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 6% of all known vulnerabilities).

Severity (CVSS 3.1)4.7Medium

Exploit odds (30 days)0.2%top 94.3% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

Zen is a firefox-based browser. Prior to 1.19.12b, the ZEN Browser incorrectly truncates long hostnames in the address bar and shows only the attacker-controlled prefix of the subdomain, hiding the actual registrable domain (eTLD+1). As a result, an attacker can craft extremely long malicious subdomains that visually imitate trusted brands, and the browser will display only the spoofed prefix, misleading users about the actual origin of the site. This directly compromises the URL bar as a security indicator and creates a phishing/supply-chain attack vector. This vulnerability is fixed in 1.19.12b.

Affected products (as reported)

Vendor	Product	Versions
zen-browser	desktop	< 1.19.12b

Weakness: CWE-451 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N

References

https://github.com/zen-browser/desktop/security/advisories/GHSA-7p2r-fp29-9w69 x_refsource_CONFIRM