CVE-2021-43532Public exploitNetwork attack vector

Authentication-token disclosure via redirected image links

Published Dec 8, 2021 · Updated Aug 4, 2024

Information disclosure in Mozilla Firefox before 94 allows remote attackers to steal authentication tokens through a crafted page. The Copy Image Link context-menu handler copied the post-redirect image URL, including an intermediate URL retained when Content Security Policy stopped the chain. Exploitation requires a user to visit a crafted page and paste the copied link back into it, exposing a URL-borne token that can enable account takeover.

CVSS severity6.1
Medium
EPSS probability0.53%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Information disclosure in Mozilla Firefox before 94 allows remote attackers to steal authentication tokens through a crafted page. The Copy Image Link context-menu handler copied the post-redirect image URL, including an intermediate URL retained when Content Security Policy stopped the chain. Exploitation requires a user to visit a crafted page and paste the copied link back into it, exposing a URL-borne token that can enable account takeover.

The record

CVE
CVE-2021-43532
Published
Dec 8, 2021
Updated
Aug 4, 2024
Vendor
Mozilla
Product
Firefox
Classifications
CWE-601, T1204
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

5.8NIST NVDAV:N/AC:M/Au:N/C:P/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.

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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

CWE-601URL Redirection to Untrusted Site ('Open Redirect')
T1204User 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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