CVE-2021-43530Public exploitNetwork attack vector

Universal XSS via unrestricted QR URL loading

Published Dec 8, 2021 · Updated Aug 4, 2024

Universal XSS in Mozilla Firefox for Android before 94 allows remote attackers to execute script in another site's context via a QR code. SearchDialogFragment passed the scanned result to openToBrowserAndLoad without external URL-load flags, allowing javascript: and data: schemes to execute. A user must scan the crafted code and approve its prompt; the script then runs in the current page origin and can read or alter accessible site data.

CVSS severity6.1
Medium
EPSS probability1.39%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Universal XSS in Mozilla Firefox for Android before 94 allows remote attackers to execute script in another site's context via a QR code. SearchDialogFragment passed the scanned result to openToBrowserAndLoad without external URL-load flags, allowing javascript: and data: schemes to execute. A user must scan the crafted code and approve its prompt; the script then runs in the current page origin and can read or alter accessible site data.

The record

CVE
CVE-2021-43530
Published
Dec 8, 2021
Updated
Aug 4, 2024
Vendor
Mozilla
Product
Firefox
Classifications
T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 8, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=unspecified <94

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mozilla · Firefoxversion=unspecified <94

Published CVSS scores

4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:P/A:N
6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

T1203Exploitation for Client Execution

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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