How severe is CVE-2021-34859?

CVE-2021-34859 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-34859 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 9% (95th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-34859?

CVE-2021-34859 affects Teamviewer. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-34859?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-34859 published?

CVE-2021-34859 was published on 2021-10-25 and last updated on 2026-06-17.

CVE-2021-34859

CVE-2021-34859 is a high-severity vulnerability in Teamviewer with a CVSS 3.x base score of 8.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-787.

Key facts

Severity: High (CVSS 3.x base score 8.8)
CVSS v2: 6.8
EPSS exploit prediction: 9% (95th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-787
Affected product: Teamviewer
Published: 2021-10-25
Last modified: 2026-06-17

Description

This vulnerability allows remote attackers to execute arbitrary code on affected installations of TeamViewer 15.16.8.0. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file. The specific flaw exists within the parsing of TVS files. The issue results from the lack of proper validation of user-supplied data, which can result in a memory corruption condition. An attacker can leverage this vulnerability to execute code in the context of the current process. Was ZDI-CAN-13697.

Frequently asked questions

What is CVE-2021-34859?: This vulnerability allows remote attackers to execute arbitrary code on affected installations of TeamViewer 15.16.8.0. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file. The specific flaw exists within the parsing of TVS files. The issue results from the lack of proper validation of user-supplied data, which can result in a memory corruption condition. An attacker can leverage this vulnerability to execute code in the context of the current process. Was ZDI-CAN-13697.
How severe is CVE-2021-34859?: CVE-2021-34859 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-34859 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 9% (95th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-34859?: CVE-2021-34859 affects Teamviewer. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-34859?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-34859 published?: CVE-2021-34859 was published on 2021-10-25 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:teamviewer:teamviewer:15.16.8.0:*:*:*:*:*:*:*

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