Vulnerability · Published Jun 16, 2026 · Assigned by mozilla
CVE-2026-53899Cross-origin cookies could be leaked when opening a PDF link
Medium 6.5
In plain English
A medium-severity insufficient verification of data authenticity 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 0.1% (higher than 1% of all known vulnerabilities).
Severity (CVSS 3.1)6.5Medium
Exploit odds (30 days)<0.1%top 99.3% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
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.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Mozilla | Firefox for iOS | see references |
Weakness: CWE-345 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N