How severe is CVE-2021-3571?

CVE-2021-3571 has a CVSS 3.x base score of 7.1, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability high.

Is CVE-2021-3571 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (77th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-3571?

CVE-2021-3571 primarily affects Redhat Enterprise Linux. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-3571?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-3571 published?

CVE-2021-3571 was published on 2021-07-09 and last updated on 2026-06-17.

CVE-2021-3571

CVE-2021-3571 is a high-severity vulnerability in Redhat Enterprise Linux with a CVSS 3.x base score of 7.1. 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-125.

Key facts

Severity: High (CVSS 3.x base score 7.1)
CVSS v2: 5.5
EPSS exploit prediction: 2% (77th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-125
Affected product: Redhat Enterprise Linux
Published: 2021-07-09
Last modified: 2026-06-17

Description

A flaw was found in the ptp4l program of the linuxptp package. When ptp4l is operating on a little-endian architecture as a PTP transparent clock, a remote attacker could send a crafted one-step sync message to cause an information leak or crash. The highest threat from this vulnerability is to data confidentiality and system availability. This flaw affects linuxptp versions before 3.1.1 and before 2.0.1.

Frequently asked questions

What is CVE-2021-3571?: A flaw was found in the ptp4l program of the linuxptp package. When ptp4l is operating on a little-endian architecture as a PTP transparent clock, a remote attacker could send a crafted one-step sync message to cause an information leak or crash. The highest threat from this vulnerability is to data confidentiality and system availability. This flaw affects linuxptp versions before 3.1.1 and before 2.0.1.
How severe is CVE-2021-3571?: CVE-2021-3571 has a CVSS 3.x base score of 7.1, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability high.
Is CVE-2021-3571 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (77th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-3571?: CVE-2021-3571 primarily affects Redhat Enterprise Linux. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-3571?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-3571 published?: CVE-2021-3571 was published on 2021-07-09 and last updated on 2026-06-17.

References

Affected products (4)

cpe:2.3:a:linuxptp_project:linuxptp:*:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:-:*:*:*
cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*

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