CVE-2021-33879Public exploitNetwork attack vector

Code execution via attacker-controlled update metadata

Published Jun 6, 2021 · Updated Aug 4, 2024

Code execution in Tencent GameLoop before 4.1.21.90 allows attackers to launch arbitrary Windows executables via intercepted HTTP updates. The updater accepts an attacker-modified ComponentUpdate.xml URL and MD5 value, then treats the matching downloaded file as a legitimate update and executes it. Exploitation requires a network position capable of modifying the HTTP response and a victim who initiates an update and selects Update Now.

CVSS severity8.1
High
EPSS probability1.02%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Code execution in Tencent GameLoop before 4.1.21.90 allows attackers to launch arbitrary Windows executables via intercepted HTTP updates. The updater accepts an attacker-modified ComponentUpdate.xml URL and MD5 value, then treats the matching downloaded file as a legitimate update and executes it. Exploitation requires a network position capable of modifying the HTTP response and a victim who initiates an update and selects Update Now.

The record

CVE
CVE-2021-33879
Published
Jun 6, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-494, T1195.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 6, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

8.1NISTCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
6.8NISTAV:N/AC:M/Au:N/C:P/I:P/A:P

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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-494Download of Code Without Integrity Check
T1195.002Compromise Software Supply Chain

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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