Vulnerability · Published Jun 1, 2026 · Assigned by mozilla

CVE-2026-9309Arbitrary JavaScript execution in internal pages via Reader View JSON-LD injection

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 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.

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

In plain English

Official description

Affected products (as reported)

References