CVE-2026-9308

Arbitrary JavaScript execution in Reader View due to wrong HTML replacement order

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 replaced page content in its HTML template before replacing other internal placeholders. A malicious page could include a placeholder string that was later substituted with JSON-LD data, potentially resulting in arbitrary JavaScript execution. 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 Reader View due to wrong HTML replacement order
    cvelistv5