Firefox iOS Reader View XSS via JSONLD (fixed in v151.2)
CVE-2026-9309 Published on June 1, 2026
Arbitrary JavaScript execution in internal pages via Reader View JSON-LD injection
Firefox for iOS Reader View did not properly escape HTML tags in JSON-LD metadata. A malicious page could inject markup that changed Reader View behavior and leaked sensitive URL parameters. These parameters could then be used to access internal pages, potentially resulting in arbitrary JavaScript execution in an internal origin. This vulnerability was fixed in Firefox for iOS 151.2.
Vulnerability Analysis
CVE-2026-9309 can be exploited with network access, requires user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have a small impact on confidentiality and integrity, and no impact on availability.
Weakness Type
What is a XSS Vulnerability?
The software does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.
CVE-2026-9309 has been classified to as a XSS vulnerability or weakness.
Products Associated with CVE-2026-9309
Want to know whenever a new CVE is published for Mozilla Firefox? stack.watch will email you.
Affected Versions
Mozilla Firefox for iOS:- Version 151.2, <= * is unaffected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.