CVE-2026-53899

Cross-origin cookies could be leaked when opening a PDF link

Medium · published June 16, 2026

CVSS v3.1
6.5
EPSS
0%
Percentile
2.8
In the wild
Unconfirmed
What it is

Firefox for iOS used partial domain matching when attaching cookies to PDF requests, allowing a malicious site on a suffix domain to receive cookies belonging to the target site. This vulnerability was fixed in Firefox for iOS 152.0.

The record
Technical detail
CVSS v3.1
6.5 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
CVSS v4.0
Not supplied
EPSS
0.00137 · 2.8th percentile
Published
2026-06-16T11:53Z
EPSS history
Timeline
  • 16 JUN 11:53Z
    Cross-origin cookies could be leaked when opening a PDF link
    cvelistv5