CVE-2021-43042

CRITICALNVD 9.89.8—Trending — 3 sources updated this week

9.8

An issue was discovered in Kaseya Unitrends Backup Appliance before 10.5.5. A buffer overflow existed in the vaultServer component. This was exploitable by a remote unauthenticated attacker.

CVSS v3: 9.8
EG Score: 9.8(medium)
EPSS: 87.4%
KEV: Not listed

Published

December 6, 2021

Last Modified

November 21, 2024

References (6)

cve@mitrehttps://helpdesk.kaseya.com/hc/en-gb/articles/4412762258961
cve@mitrehttps://www.cyberonesecurity.com/blog/exploiting-kaseya-unitrends-backup-appliance-part-1
cve@mitrehttps://www.cyberonesecurity.com/blog/exploiting-kaseya-unitrends-backup-appliance-part-2
af854a3a-2127-422b-91ae-364da2661108https://helpdesk.kaseya.com/hc/en-gb/articles/4412762258961
af854a3a-2127-422b-91ae-364da2661108https://www.cyberonesecurity.com/blog/exploiting-kaseya-unitrends-backup-appliance-part-1
af854a3a-2127-422b-91ae-364da2661108https://www.cyberonesecurity.com/blog/exploiting-kaseya-unitrends-backup-appliance-part-2

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

CWE-120Buffer Copy without Checking Size (Classic Buffer Overflow)

Data Freshness Timeline

(refreshed 11× in last 7d / 11× in last 30d)

Every time one of our enrichment pipelines (NVD, MITRE cvelistV5, EPSS, CISA KEV, GHSA, OSV, vendor advisories) ran against this CVE. Most recent first.

2026-05-28 13:43 UTCepss_batch
2026-05-28 13:43 UTCepss_batch
2026-05-27 13:39 UTCepss_batch
2026-05-27 13:39 UTCepss_batch
2026-05-26 13:42 UTCepss_batch
2026-05-26 13:42 UTCepss_batch
2026-05-26 07:17 UTCepss_batch
2026-05-26 07:17 UTCepss_batch
2026-05-26 07:17 UTCepss_batch
2026-05-26 06:54 UTCEG score recompute
2026-05-26 06:54 UTCGHSA enrichment

Frequently asked(5)

What is CVE-2021-43042?

CVE-2021-43042 is a critical vulnerability published on December 6, 2021. An issue was discovered in Kaseya Unitrends Backup Appliance before 10.5.5. A buffer overflow existed in the vaultServer component. This was exploitable by a remote unauthenticated attacker.

When was CVE-2021-43042 disclosed?

CVE-2021-43042 was first published in the National Vulnerability Database on December 6, 2021, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.

Is CVE-2021-43042 actively exploited?

CVE-2021-43042 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 87.4% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.

What is the CVSS score of CVE-2021-43042?

CVE-2021-43042 has a CVSS v3 base score of 9.8 (NVD).

How do I remediate CVE-2021-43042?

Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-43042, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2021-43042

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CVE-2021-43042

📅 Published

🔄 Last Modified

🔗 References (6)