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CVE-2021-4221

MEDIUM
4.3
CVSS Score
Published: December 22, 2022 at 12:00 AM UTC
Updated: June 17, 2026 at 04:19 AM UTC
1 product affected across 1 vendorFirefox· also runs on 1 platform

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Severity
MEDIUM4.3
Exploit prediction
EPSS 0.4%
SSVC
PoC

Description

If a domain name contained a RTL character, it would cause the domain to be rendered to the right of the path. This could lead to user confusion and spoofing attacks. <br>*This bug only affects Firefox for Android. Other operating systems are unaffected.*<br>*Note*: Due to a clerical error this advisory was not included in the original announcement, and was added in Feburary 2022. This vulnerability affects Firefox < 92.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Firefox· Mozilla
95%
v < 92
Affected range stops below 92, so it looks safe — our inference, not a vendor statement
Affected range stops below 92.0, so it looks safe — our inference, not a vendor statement
google-android (environment)

Runs on — not affected

The affected product only carries this flaw when running on these platforms. The platforms themselves are not vulnerable.

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (2)

ExploitIssue TrackingVendor Advisory
Source: [email protected]
https://bugzilla.mozilla.org/show_bug.cgi?id=1704422
Vendor Advisory
Source: [email protected]
https://www.mozilla.org/security/advisories/mfsa2021-38/

SSVC — Action Prioritization

SSVCPoCNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

4.3MEDIUMCISA-ADP
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
NONE
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
NVD-CWE-OtherCWE-1007

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