Privilege escalation in the Reader View component in Firefox for iOS
Affects Firefox for iOS before 160.0, where the Reader View component is flawed. CVSS rates it High (8.8). Fixed in Firefox for iOS 160.0.
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: Check whether your setup matches what the bug needs. Affects Firefox for iOS; fixed in Firefox for iOS 160.0
- 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 the Reader View component of Firefox for iOS lets an attacker gain higher privileges than they should have. The flaw is fixed in later releases of the browser.
Read the original description
Privilege escalation in the Reader View component 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
Check whether your setup matches what the bug needs.
Affects Firefox for iOS; fixed in Firefox for iOS 160.0Upgrade 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-2026-121842
Is CVE-2026-121842 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 Reader View component of Firefox for iOS contains a flaw that allows privilege escalation. The advisory describes the impact only as privilege escalation in that component.Source: mozilla.org
Am I affected, and how do I check?
The advisory lists Firefox for iOS versions before 160.0 as affected, since 160.0 is the release that fixes the issue. To check, compare the installed Firefox for iOS version with 160.0.Source: mozilla.org
How do I fix CVE-2026-121842?
Update Firefox for iOS to version 160.0 or later, which contains the fix. The sources give no workaround.Source: mozilla.org