CVE-2021-24027Public exploit

TLS secret disclosure via externally readable cache

Published Apr 6, 2021 · Updated Aug 3, 2024

Sensitive-data exposure in WhatsApp for Android and WhatsApp Business for Android before 2.21.4.18 allows attackers to read TLS material. The apps store TLS 1.2 master-key material in SSLSessionCache under the external cache directory, where other apps can read it. Access requires external-storage permission on Android 9 or earlier, or legacy external-storage access on Android 10, and enables communication decryption or modification.

CVSS severity7.5
High
EPSS probability3.81%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Sensitive-data exposure in WhatsApp for Android and WhatsApp Business for Android before 2.21.4.18 allows attackers to read TLS material. The apps store TLS 1.2 master-key material in SSLSessionCache under the external cache directory, where other apps can read it. Access requires external-storage permission on Android 9 or earlier, or legacy external-storage access on Android 10, and enables communication decryption or modification.

The record

CVE
CVE-2021-24027
Published
Apr 6, 2021
Updated
Aug 3, 2024
Vendor
Meta Platforms, Inc.
Product
WhatsApp for Android
Classifications
CWE-524, T1533
Attack vector
local
Privileges
Unavailable

Timeline

How it unfolded

  1. Apr 6, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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 <v2.21.4.18

What conditions does exploitation require?

Attack vectorlocal
Required privilegesUnavailable in this record.

What is affected?

Meta Platforms, Inc. · WhatsApp for Androidversion=unspecified <v2.21.4.18
Meta Platforms, Inc. · WhatsApp Business for Androidversion=v2.21.4.18

Published CVSS scores

5.0NVDAV:N/AC:L/Au:N/C:P/I:N/A:N
7.5NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-524Use of Cache Containing Sensitive Information
T1533Data from Local System

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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