Privilege escalation in Firefox for iOS
Mozilla's Firefox for iOS has a privilege escalation bug, fixed in Firefox for iOS 160. CVSS rates it 8.8 (high), and no vendor severity is listed.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in Firefox for iOS 160
- Who is exposed
- Specific setups only
Do first: Upgrade to a fixed version: Firefox for iOS 160.
- Last modified
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 22/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Specific setups only
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: none
- Automatable: no
- Technical impact: total
Summary
Privilege escalation in Firefox for iOS lets an attacker gain higher access than they should have. The advisory does not give details on how the flaw is reached, and it is fixed in a newer release.
Read the original description
Privilege escalation in Firefox for iOS. This vulnerability was fixed in Firefox for iOS 160.0.
cve.now Index
- Exploitation0/40No signal
- Exposure12/25Specific setups only, reachable over the network without a login
- Reach?/20Unknown. No tracked technology or package matched
- Severity9.8/10CVSS 8.8, total technical impact per CISA
- No patch0/5No signal
What would change the score
- Would score about 72 if added to CISA KEV
- Would score about 67 if CISA's SSVC rates exploitation active
What to do
Upgrade to a fixed version: Firefox for iOS 160.
Timeline
- CVE published
- First seen by cve.now
- CISA SSVC assessment
Exploitation: none · Automatable: no · Technical impact: total
- Record last updated
Affected versions
- Mozilla Firefox for iOS
Version range not reported
Evidence 2
- Link
- Link
Corrections
None so far.
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Questions about CVE-2026-121843
Is CVE-2026-121843 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
What does this mean?
The bug lets an attacker gain higher privileges than the app is meant to allow. The checked facts do not describe the exact mechanism.Source: mozilla.org
Am I affected, and how do I check?
The checked facts do not list an affected version range or specific setup conditions. The fix is in Firefox for iOS 160, so the installed version can be compared against 160 in the app's About screen or the App Store update list.Source: mozilla.org
How do I fix CVE-2026-121843?
Update Firefox for iOS to version 160 or later.Source: mozilla.org