What is CVE-2026-9078?

CVE-2026-9078 is a medium-severity vulnerability in Mozilla Firefox, classified under User Interface (UI) Misrepresentation of Critical Information. CVSS score: 5.4/10. Published 2026-05-25.

How severe is CVE-2026-9078?

Medium severity. CVSS v3 base score is 5.4 out of 10.

Vulnerability in Mozilla Firefox

CVE-2026-9078

Firefox for iOS displayed specially crafted right-to-left (RTL) and internationalized domain names (IDNs) incorrectly in link preview UI surfaces. A crafted RTL hostname could visually reorder portions of the displayed domain, causing attacker-controlled sites to appear as trusted origins. This vulnerability was fixed in Firefox for iOS 151.1.

Published 2026-05-25 · last modified 2026-07-23.

CVSS v3 metric

CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:L.

EPSS exploit prediction

EPSS: 0.003 (15.7th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 16th percentile — 15.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.002 · newest: 0.003 · change: +0.001

Affected products

Mozilla Firefox
Mozilla Firefox For iOS — versions 151.1

Weakness classification (CWE)

CWE-451 — User Interface (UI) Misrepresentation of Critical Information

References

bugzilla.mozilla.org/show_bug.cgi (Permissions Required)
www.mozilla.org/security/advisories/mfsa2026-52/ (Vendor Advisory)

Frequently asked questions

What is CVE-2026-9078?: CVE-2026-9078 is a medium-severity vulnerability in Mozilla Firefox, classified under User Interface (UI) Misrepresentation of Critical Information. CVSS score: 5.4/10. Published 2026-05-25.
How severe is CVE-2026-9078?: Medium severity. CVSS v3 base score is 5.4 out of 10.