How severe is CVE-2021-33191?

CVE-2021-33191 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-2021-33191 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 4% (89th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-33191?

CVE-2021-33191 affects Apache Nifi Minifi C++. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-33191?

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-2021-33191 published?

CVE-2021-33191 was published on 2021-08-24 and last updated on 2026-06-17.

CVE-2021-33191

CVE-2021-33191 is a critical-severity vulnerability in Apache Nifi Minifi C++ 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-78.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 4% (89th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-78
Affected product: Apache Nifi Minifi C++
Published: 2021-08-24
Last modified: 2026-06-17

Description

From Apache NiFi MiNiFi C++ version 0.5.0 the c2 protocol implements an "agent-update" command which was designed to patch the application binary. This "patching" command defaults to calling a trusted binary, but might be modified to an arbitrary value through a "c2-update" command. Said command is then executed using the same privileges as the application binary. This was addressed in version 0.10.0

Frequently asked questions

What is CVE-2021-33191?: From Apache NiFi MiNiFi C++ version 0.5.0 the c2 protocol implements an "agent-update" command which was designed to patch the application binary. This "patching" command defaults to calling a trusted binary, but might be modified to an arbitrary value through a "c2-update" command. Said command is then executed using the same privileges as the application binary. This was addressed in version 0.10.0
How severe is CVE-2021-33191?: CVE-2021-33191 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-2021-33191 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 4% (89th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-33191?: CVE-2021-33191 affects Apache Nifi Minifi C++. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-33191?: 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-2021-33191 published?: CVE-2021-33191 was published on 2021-08-24 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:apache:nifi_minifi_c\+\+:*:*:*:*:*:*:*:*

More vulnerabilities in Apache Nifi Minifi C++

CVE-2023-41180 — Medium (CVSS 5.9): Incorrect certificate validation in InvokeHTTP on Apache NiFi MiNiFi C++ versions 0.13 to 0.14 allows an intermediary…

All CVEs affecting Apache Nifi Minifi C++ →

Other CWE-78 (OS Command Injection) vulnerabilities

CVE-2026-56004 — Critical (CVSS 10.0): A shellcode injection in the mercurial handler of the obs tar_scm source service before version 0.12.4 could be used by…
CVE-2026-56415 — Critical (CVSS 10.0): Storage Concentrator (SC & SCVM) contains a command injection vulnerability within the debug.pl script that is…
CVE-2026-56413 — Critical (CVSS 10.0): Storage Concentrator (SC & SCVM) contains a command injection vulnerability in the ms_service.pl service, which listens…
CVE-2026-49869 — Critical (CVSS 10.0): Kestra is an open-source, event-driven orchestration platform. Prior to 1.0.45 and 1.3.21, AuthenticationFilter in…
CVE-2026-49261 — Critical (CVSS 10.0): MariaDB server is a community developed fork of MySQL server. Versions 10.6.1 through 10.6.26, 10.11.1 through…
CVE-2026-10520 — Critical (CVSS 10.0): An OS Command Injection vulnerability in Ivanti Sentry before the R10.5.2, R10.6.2 and R10.7.1 versions allows a…

Browse all CWE-78 (OS Command Injection) vulnerabilities →