Vulnerability in Mozilla Firefox For Ios

CVE-2026-53900

Firefox for iOS preserved cookies set on the initial PDF request across cross-origin HTTP redirects in TemporaryDocument, allowing a malicious site to inject arbitrary cookies into requests to an unrelated target domain. This vulnerability…

CVSS v3 metric

CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N.

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-53900?
CVE-2026-53900 is a medium-severity vulnerability in Mozilla Firefox For Ios, classified under Insufficient Verification of Data Authenticity. CVSS score: 4.3/10. Published 2026-06-16.
How severe is CVE-2026-53900?
Medium severity. CVSS v3 base score is 4.3 out of 10.