How severe is CVE-2021-35971?

CVE-2021-35971 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-35971 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (66th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-35971?

CVE-2021-35971 affects Veeam Veeam Backup & Replication. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-35971?

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

When was CVE-2021-35971 published?

CVE-2021-35971 was published on 2021-06-30 and last updated on 2026-06-17.

CVE-2021-35971

CVE-2021-35971 is a critical-severity vulnerability in Veeam Veeam Backup & Replication with a CVSS 3.x base score of 9.8. 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-502.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 1% (66th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-502
Affected product: Veeam Veeam Backup & Replication
Published: 2021-06-30
Last modified: 2026-06-17

Description

Veeam Backup and Replication 10 before 10.0.1.4854 P20210609 and 11 before 11.0.0.837 P20210507 mishandles deserialization during Microsoft .NET remoting.

Frequently asked questions

What is CVE-2021-35971?: Veeam Backup and Replication 10 before 10.0.1.4854 P20210609 and 11 before 11.0.0.837 P20210507 mishandles deserialization during Microsoft .NET remoting.
How severe is CVE-2021-35971?: CVE-2021-35971 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-35971 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (66th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-35971?: CVE-2021-35971 affects Veeam Veeam Backup & Replication. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-35971?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2021-35971 published?: CVE-2021-35971 was published on 2021-06-30 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:veeam:veeam_backup_\&_replication:*:*:*:*:*:*:*:*

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