How severe is CVE-2021-42099?

CVE-2021-42099 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-2021-42099 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 7% (93rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-42099?

CVE-2021-42099 primarily affects Zohocorp Manageengine M365 Manager Plus. In total, 104 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-42099?

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-2021-42099 published?

CVE-2021-42099 was published on 2021-11-30 and last updated on 2026-06-17.

CVE-2021-42099

CVE-2021-42099 is a critical-severity vulnerability in Zohocorp Manageengine M365 Manager Plus 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-434.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 7% (93rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-434
Affected product: Zohocorp Manageengine M365 Manager Plus
Published: 2021-11-30
Last modified: 2026-06-17

Description

Zoho ManageEngine M365 Manager Plus before 4421 is vulnerable to file-upload remote code execution.

Frequently asked questions

What is CVE-2021-42099?: Zoho ManageEngine M365 Manager Plus before 4421 is vulnerable to file-upload remote code execution.
How severe is CVE-2021-42099?: CVE-2021-42099 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-2021-42099 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 7% (93rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-42099?: CVE-2021-42099 primarily affects Zohocorp Manageengine M365 Manager Plus. In total, 104 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-42099?: 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-2021-42099 published?: CVE-2021-42099 was published on 2021-11-30 and last updated on 2026-06-17.

References

Affected products (104)

cpe:2.3:a:zohocorp:manageengine_m365_manager_plus:-:*:*:*:*:*:*:*
cpe:2.3:a:zohocorp:manageengine_m365_manager_plus:build_4000:*:*:*:*:*:*:*
cpe:2.3:a:zohocorp:manageengine_m365_manager_plus:build_4001:*:*:*:*:*:*:*
cpe:2.3:a:zohocorp:manageengine_m365_manager_plus:build_4002:*:*:*:*:*:*:*
cpe:2.3:a:zohocorp:manageengine_m365_manager_plus:build_4003:*:*:*:*:*:*:*
cpe:2.3:a:zohocorp:manageengine_m365_manager_plus:build_4004:*:*:*:*:*:*:*
cpe:2.3:a:zohocorp:manageengine_m365_manager_plus:build_4005:*:*:*:*:*:*:*
cpe:2.3:a:zohocorp:manageengine_m365_manager_plus:build_4007:*:*:*:*:*:*:*
cpe:2.3:a:zohocorp:manageengine_m365_manager_plus:build_4008:*:*:*:*:*:*:*
cpe:2.3:a:zohocorp:manageengine_m365_manager_plus:build_4009:*:*:*:*:*:*:*
cpe:2.3:a:zohocorp:manageengine_m365_manager_plus:build_4010:*:*:*:*:*:*:*
cpe:2.3:a:zohocorp:manageengine_m365_manager_plus:build_4011:*:*:*:*:*:*:*
cpe:2.3:a:zohocorp:manageengine_m365_manager_plus:build_4012:*:*:*:*:*:*:*
cpe:2.3:a:zohocorp:manageengine_m365_manager_plus:build_4013:*:*:*:*:*:*:*
cpe:2.3:a:zohocorp:manageengine_m365_manager_plus:build_4014:*:*:*:*:*:*:*
cpe:2.3:a:zohocorp:manageengine_m365_manager_plus:build_4100:*:*:*:*:*:*:*
cpe:2.3:a:zohocorp:manageengine_m365_manager_plus:build_4101:*:*:*:*:*:*:*
cpe:2.3:a:zohocorp:manageengine_m365_manager_plus:build_4102:*:*:*:*:*:*:*
cpe:2.3:a:zohocorp:manageengine_m365_manager_plus:build_4103:*:*:*:*:*:*:*
cpe:2.3:a:zohocorp:manageengine_m365_manager_plus:build_4104:*:*:*:*:*:*:*
cpe:2.3:a:zohocorp:manageengine_m365_manager_plus:build_4105:*:*:*:*:*:*:*
cpe:2.3:a:zohocorp:manageengine_m365_manager_plus:build_4106:*:*:*:*:*:*:*
cpe:2.3:a:zohocorp:manageengine_m365_manager_plus:build_4108:*:*:*:*:*:*:*
cpe:2.3:a:zohocorp:manageengine_m365_manager_plus:build_4109:*:*:*:*:*:*:*
cpe:2.3:a:zohocorp:manageengine_m365_manager_plus:build_4110:*:*:*:*:*:*:*
cpe:2.3:a:zohocorp:manageengine_m365_manager_plus:build_4111:*:*:*:*:*:*:*
cpe:2.3:a:zohocorp:manageengine_m365_manager_plus:build_4112:*:*:*:*:*:*:*
cpe:2.3:a:zohocorp:manageengine_m365_manager_plus:build_4113:*:*:*:*:*:*:*
cpe:2.3:a:zohocorp:manageengine_m365_manager_plus:build_4115:*:*:*:*:*:*:*
cpe:2.3:a:zohocorp:manageengine_m365_manager_plus:build_4116:*:*:*:*:*:*:*
cpe:2.3:a:zohocorp:manageengine_m365_manager_plus:build_4117:*:*:*:*:*:*:*
cpe:2.3:a:zohocorp:manageengine_m365_manager_plus:build_4118:*:*:*:*:*:*:*
cpe:2.3:a:zohocorp:manageengine_m365_manager_plus:build_4119:*:*:*:*:*:*:*
cpe:2.3:a:zohocorp:manageengine_m365_manager_plus:build_4200:*:*:*:*:*:*:*
cpe:2.3:a:zohocorp:manageengine_m365_manager_plus:build_4201:*:*:*:*:*:*:*
cpe:2.3:a:zohocorp:manageengine_m365_manager_plus:build_4202:*:*:*:*:*:*:*
cpe:2.3:a:zohocorp:manageengine_m365_manager_plus:build_4203:*:*:*:*:*:*:*
cpe:2.3:a:zohocorp:manageengine_m365_manager_plus:build_4204:*:*:*:*:*:*:*
cpe:2.3:a:zohocorp:manageengine_m365_manager_plus:build_4205:*:*:*:*:*:*:*
cpe:2.3:a:zohocorp:manageengine_m365_manager_plus:build_4206:*:*:*:*:*:*:*

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