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VulnerabilityPublished

CVE-2026-53900: Mozilla Firefox for iOS · CWE-345

Affects Mozilla Firefox for iOSSource CVE Database V5

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Not known to be exploited · CVSS 4.3 Medium · fixed in 152.0 : update Mozilla Firefox for iOS when convenient.

Data as of 30 Oct 2026, 20:25 UTC

CVSS 3.1 base score
4.3Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% 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:R/S:U/C:L/I:N/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 16 Jun 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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 as the vendor advisory confirms the availability of an official fix.

Description

CVE-2026-53900 is a medium severity vulnerability in Mozilla Firefox for iOS where cookies set on an initial PDF request are preserved across cross-origin HTTP redirects in TemporaryDocument. This behavior allows a malicious site to inject arbitrary cookies into requests to unrelated target domains. The issue was fixed in Firefox for iOS version 152.0.

References

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