How severe is CVE-2021-43041?

CVE-2021-43041 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-43041 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (81st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-43041?

CVE-2021-43041 affects Kaseya Unitrends Backup. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-43041?

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-2021-43041 published?

CVE-2021-43041 was published on 2021-12-06 and last updated on 2026-06-17.

CVE-2021-43041

CVE-2021-43041 is a high-severity vulnerability in Kaseya Unitrends Backup 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-134.

Key facts

Severity: High (CVSS 3.x base score 8.8)
CVSS v2: 6.5
EPSS exploit prediction: 2% (81st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-134
Affected product: Kaseya Unitrends Backup
Published: 2021-12-06
Last modified: 2026-06-17

Description

An issue was discovered in Kaseya Unitrends Backup Appliance before 10.5.5. A crafted HTTP request could induce a format string vulnerability in the privileged vaultServer application.

Frequently asked questions

What is CVE-2021-43041?: An issue was discovered in Kaseya Unitrends Backup Appliance before 10.5.5. A crafted HTTP request could induce a format string vulnerability in the privileged vaultServer application.
How severe is CVE-2021-43041?: CVE-2021-43041 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-43041 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (81st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-43041?: CVE-2021-43041 affects Kaseya Unitrends Backup. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-43041?: 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-2021-43041 published?: CVE-2021-43041 was published on 2021-12-06 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:kaseya:unitrends_backup:*:*:*:*:*:*:*:*

More vulnerabilities in Kaseya Unitrends Backup

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Other CWE-134 vulnerabilities

CVE-2012-1851 — Critical (CVSS 10.0): Format string vulnerability in the Print Spooler service in Microsoft Windows XP SP2 and SP3, Windows Server 2003 SP2,…
CVE-2012-0242 — Critical (CVSS 10.0): Format string vulnerability in Advantech/BroadWin WebAccess before 7.0 allows remote attackers to execute arbitrary…
CVE-2011-2475 — Critical (CVSS 10.0): Format string vulnerability in ECTrace.dll in the iMailGateway service in the Internet Mail Gateway in OneBridge Server…
CVE-2011-1568 — Critical (CVSS 10.0): Format string vulnerability in the logText function in shmemmgr9.dll in IGSSdataServer.exe 9.00.00.11074, and…
CVE-2010-4235 — Critical (CVSS 10.0): Format string vulnerability in RealNetworks Helix Server 12.x, 13.x, and 14.x before 14.2, and Helix Mobile Server…
CVE-2011-0270 — Critical (CVSS 10.0): Format string vulnerability in nnmRptConfig.exe in HP OpenView Network Node Manager (OV NNM) 7.51 and 7.53 allows…

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