CVE-2021-34858

Code execution via TVS parser out-of-bounds read

Published Jan 13, 2022 · Updated Aug 4, 2024

Out-of-bounds read in TeamViewer Desktop Clients 15.16.8.0 allows remote attackers to execute code via a crafted TVS file. The TVS parser fails to validate user-supplied recording data before reading past the end of an allocated structure. Exploitation requires user interaction to open a malicious file or visit a malicious page and, for remote delivery, an additional vulnerability; successful exploitation runs code in the current process or crashes it.

CVSS severity7.8
High
EPSS probability3.76%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds read in TeamViewer Desktop Clients 15.16.8.0 allows remote attackers to execute code via a crafted TVS file. The TVS parser fails to validate user-supplied recording data before reading past the end of an allocated structure. Exploitation requires user interaction to open a malicious file or visit a malicious page and, for remote delivery, an additional vulnerability; successful exploitation runs code in the current process or crashes it.

The record

CVE
CVE-2021-34858
Published
Jan 13, 2022
Updated
Aug 4, 2024
Vendor
TeamViewer
Product
TeamViewer Desktop Clients
Classifications
CWE-125, T1204.002, T1203
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 13, 2022CVE 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=15.16.8.0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

TeamViewer · TeamViewer Desktop Clientsversion=15.16.8.0

Published CVSS scores

7.8Zero Day InitiativeCVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
7.8NVDCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
6.8NVDAV: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.

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)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-125Out-of-bounds Read
T1204.002User Execution: Malicious File
T1203Exploitation for Client Execution

Public exploit references

No public exploit references are available in this record.

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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