CVE-2026-9309

Arbitrary JavaScript execution in internal pages via Reader View JSON-LD injection

Medium · published June 1, 2026

CVSS v3.1
5.4
EPSS
0%
Percentile
17.2
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
5.4 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
CVSS v4.0
Not supplied
EPSS
0.00263 · 17.2th percentile
Published
2026-06-01T11:24Z
EPSS history
Timeline
  • 01 JUN 11:24Z
    Arbitrary JavaScript execution in internal pages via Reader View JSON-LD injection
    cvelistv5