Vulnerability · Published Jun 1, 2026 · Assigned by mozilla
CVE-2026-9308Arbitrary JavaScript execution in Reader View due to wrong HTML replacement order
Medium 5.4
In plain English
A medium-severity cross-site scripting in Firefox for iOS from Mozilla. 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 5% of all known vulnerabilities).
Severity (CVSS 3.1)5.4Medium
Exploit odds (30 days)0.2%top 95.1% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
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.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Mozilla | Firefox for iOS | see references |
Weakness: CWE-79 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N