CVE-2026-9309

MEDIUM 5.4

Published 2026-06-01 · Last modified 2026-06-01

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.

NO EXPLOITATION SIGNALS

No known exploitation, public exploit, or elevated probability at this time. Track for changes.

Exploitation likelihood

0.2%chance of exploitation in 30 days · 5th percentile

○ In CISA KEV ○ Public exploit / PoC

Impact if exploited

5.4CVSS 3.1 · MEDIUM

ConfidentialityLow
IntegrityLow
AvailabilityNone

What an attacker needs

✓Access: Reachable over the network — no local access needed
✓Privileges: No account or privileges required
⚠User interaction: A user must take an action (click / open a file)
✓Complexity: No special conditions — reliably repeatable

✓ lowers the bar for an attacker · ⚠ raises it

Affected

Vendors Mozilla

Products Firefox For Ios

Weakness (CWE)

CWE-79: Cross-site scripting (XSS)

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N

References

Technical & other

Sources: NVD · CVE.org · EPSS