How severe is CVE-2021-3716?

CVE-2021-3716 has a CVSS 3.x base score of 3.1, rated low severity. It is exploitable over network with high attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.

Is CVE-2021-3716 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (43rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-3716?

CVE-2021-3716 primarily affects Redhat Enterprise Linux. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-3716?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-3716 published?

CVE-2021-3716 was published on 2022-03-02 and last updated on 2026-06-17.

CVE-2021-3716

CVE-2021-3716 is a low-severity vulnerability in Redhat Enterprise Linux with a CVSS 3.x base score of 3.1. 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-924.

Key facts

Severity: Low (CVSS 3.x base score 3.1)
CVSS v2: 3.5
EPSS exploit prediction: 1% (43rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-924
Affected product: Redhat Enterprise Linux
Published: 2022-03-02
Last modified: 2026-06-17

Description

A flaw was found in nbdkit due to to improperly caching plaintext state across the STARTTLS encryption boundary. A MitM attacker could use this flaw to inject a plaintext NBD_OPT_STRUCTURED_REPLY before proxying everything else a client sends to the server, potentially leading the client to terminate the NBD session. The highest threat from this vulnerability is to system availability.

Frequently asked questions

What is CVE-2021-3716?: A flaw was found in nbdkit due to to improperly caching plaintext state across the STARTTLS encryption boundary. A MitM attacker could use this flaw to inject a plaintext NBD_OPT_STRUCTURED_REPLY before proxying everything else a client sends to the server, potentially leading the client to terminate the NBD session. The highest threat from this vulnerability is to system availability.
How severe is CVE-2021-3716?: CVE-2021-3716 has a CVSS 3.x base score of 3.1, rated low severity. It is exploitable over network with high attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.
Is CVE-2021-3716 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (43rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-3716?: CVE-2021-3716 primarily affects Redhat Enterprise Linux. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-3716?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-3716 published?: CVE-2021-3716 was published on 2022-03-02 and last updated on 2026-06-17.

References

Affected products (3)

cpe:2.3:a:nbdkit_project:nbdkit:*:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:-:*:*:*
cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:advanced_virtualization:*:*:*

More vulnerabilities in Redhat Enterprise Linux

CVE-2015-0240 — Critical (CVSS 10.0): The Netlogon server implementation in smbd in Samba 3.5.x and 3.6.x before 3.6.25, 4.0.x before 4.0.25, 4.1.x before…
CVE-2015-0408 — Critical (CVSS 10.0): Unspecified vulnerability in Oracle Java SE 5.0u75, 6u85, 7u72, and 8u25 allows remote attackers to affect…
CVE-2014-6601 — Critical (CVSS 10.0): Unspecified vulnerability in Oracle Java SE 6u85, 7u72, and 8u25 allows remote attackers to affect confidentiality,…
CVE-2009-0846 — Critical (CVSS 10.0): The asn1_decode_generaltime function in lib/krb5/asn.1/asn1_decode.c in the ASN.1 GeneralizedTime decoder in MIT…
CVE-2007-1007 — Critical (CVSS 10.0): Format string vulnerability in GnomeMeeting 1.0.2 and earlier allows remote attackers to cause a denial of service…
CVE-2006-6235 — Critical (CVSS 10.0): A "stack overwrite" vulnerability in GnuPG (gpg) 1.x before 1.4.6, 2.x before 2.0.2, and 1.9.0 through 1.9.95 allows…

All CVEs affecting Redhat Enterprise Linux →

Other CWE-924 vulnerabilities

CVE-2025-29628 — Critical (CVSS 9.4): A Gardyn Azure IoT Hub connection string is downloaded over an insecure HTTP connection in Gardyn Home Kit firmware…
CVE-2024-44730 — Critical (CVSS 9.1): Incorrect access control in the function handleDataChannelChat(dataMessage) of Mirotalk before commit c21d58 allows…
CVE-2020-5869 — Critical (CVSS 9.1): In BIG-IQ 5.2.0-7.0.0, high availability (HA) synchronization is not secure by TLS and may allow on-path attackers to…
CVE-2025-0592 — High (CVSS 8.8): The vulnerability may allow a remote low priviledged attacker to run arbitrary shell commands by manipulating the…
CVE-2019-25719 — High (CVSS 8.6): Dräger Infinity Acute Care System and Standalone Infinity M540 patient monitors running software versions VG4.1.1,…
CVE-2021-34793 — High (CVSS 8.6): A vulnerability in the TCP Normalizer of Cisco Adaptive Security Appliance (ASA) Software and Firepower Threat Defense…

Browse all CWE-924 vulnerabilities →