CVE-2026-53899: Mozilla Firefox for iOS · CWE-345
Affects Mozilla Firefox for iOSSource CVE Database V5
Not known to be exploited · CVSS 6.5 Medium · fixed in 152.0 : update Mozilla Firefox for iOS when convenient.
Data as of 30 Oct 2026, 20:25 UTC
- EPSS
- 0.09% chance of exploitation in 30 days – higher than 0% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 152.0
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:NExploitation evidence
Disclosed: evidence found.
CVE published 16 Jun 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.
What to do
AI-suggested
This vulnerability is fixed in Firefox for iOS version 152.0. Users and administrators should update to Firefox for iOS 152.0 or later to remediate this issue. No additional mitigation steps are required beyond applying the official update from Mozilla.
Description
CVE-2026-53899 is a vulnerability in Firefox for iOS where partial domain matching was used when attaching cookies to PDF requests. This flaw allowed a malicious site on a suffix domain to receive cookies belonging to the target site. The issue was fixed in Firefox for iOS version 152.0. The vulnerability has a CVSS score of 6.5 (medium severity) and does not require user interaction or privileges to exploit. It could lead to unauthorized cookie disclosure across origins.