CVE-2021-43171Public exploitNetwork attack vector

Malicious app installation via API-supplied trust metadata

Published Aug 22, 2023 · Updated Oct 3, 2024

Cryptographic signature bypass in App Lounge before 0.19q allows attackers controlling its application server to install malicious apps. The client trusts a server-supplied SHA-1 hash for Google Play apps and lets altered package names route F-Droid apps into that unchecked path. Control of the CleanAPK application server is required; exploitation installs a new attacker-chosen app but cannot replace an installed app signed with another key.

CVSS severity6.5
Medium
EPSS probability0.41%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cryptographic signature bypass in App Lounge before 0.19q allows attackers controlling its application server to install malicious apps. The client trusts a server-supplied SHA-1 hash for Google Play apps and lets altered package names route F-Droid apps into that unchecked path. Control of the CleanAPK application server is required; exploitation installs a new attacker-chosen app but cannot replace an installed app signed with another key.

The record

CVE
CVE-2021-43171
Published
Aug 22, 2023
Updated
Oct 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-347, CAPEC-475, T1553.002
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 22, 2023CVE publishedPublication date reported by the CVE source.
  2. Oct 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-347Improper Verification of Cryptographic Signature
CAPEC-475Signature Spoofing by Improper Validation
T1553.002Code Signing

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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