How severe is CVE-2021-40865?

CVE-2021-40865 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-2021-40865 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 66% (99th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-40865?

CVE-2021-40865 affects Apache Storm. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-40865?

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-2021-40865 published?

CVE-2021-40865 was published on 2021-10-25 and last updated on 2026-06-17.

CVE-2021-40865

CVE-2021-40865 is a critical-severity vulnerability in Apache Storm with a CVSS 3.x base score of 9.8. Its EPSS exploit-prediction score of 66% places it in the 99th percentile, indicating an elevated likelihood of exploitation. 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: 66% (99th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-502
Affected product: Apache Storm
Published: 2021-10-25
Last modified: 2026-06-17

Description

An Unsafe Deserialization vulnerability exists in the worker services of the Apache Storm supervisor server allowing pre-auth Remote Code Execution (RCE). Apache Storm 2.2.x users should upgrade to version 2.2.1 or 2.3.0. Apache Storm 2.1.x users should upgrade to version 2.1.1. Apache Storm 1.x users should upgrade to version 1.2.4

Frequently asked questions

What is CVE-2021-40865?: An Unsafe Deserialization vulnerability exists in the worker services of the Apache Storm supervisor server allowing pre-auth Remote Code Execution (RCE). Apache Storm 2.2.x users should upgrade to version 2.2.1 or 2.3.0. Apache Storm 2.1.x users should upgrade to version 2.1.1. Apache Storm 1.x users should upgrade to version 1.2.4
How severe is CVE-2021-40865?: CVE-2021-40865 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-2021-40865 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 66% (99th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-40865?: CVE-2021-40865 affects Apache Storm. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-40865?: 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-2021-40865 published?: CVE-2021-40865 was published on 2021-10-25 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:apache:storm:*:*:*:*:*:*:*:*

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