How severe is CVE-2020-25583?

CVE-2020-25583 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-2020-25583 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (71st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-25583?

CVE-2020-25583 primarily affects Freebsd. In total, 29 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2020-25583?

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-2020-25583 published?

CVE-2020-25583 was published on 2021-03-29 and last updated on 2026-06-17.

CVE-2020-25583

CVE-2020-25583 is a critical-severity vulnerability in Freebsd 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-120.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 10.0
EPSS exploit prediction: 1% (71st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-120
Affected product: Freebsd
Published: 2021-03-29
Last modified: 2026-06-17

Description

In FreeBSD 12.2-STABLE before r368250, 11.4-STABLE before r368253, 12.2-RELEASE before p1, 12.1-RELEASE before p11 and 11.4-RELEASE before p5 when processing a DNSSL option, rtsold(8) decodes domain name labels per an encoding specified in RFC 1035 in which the first octet of each label contains the label's length. rtsold(8) did not validate label lengths correctly and could overflow the destination buffer.

Frequently asked questions

What is CVE-2020-25583?: In FreeBSD 12.2-STABLE before r368250, 11.4-STABLE before r368253, 12.2-RELEASE before p1, 12.1-RELEASE before p11 and 11.4-RELEASE before p5 when processing a DNSSL option, rtsold(8) decodes domain name labels per an encoding specified in RFC 1035 in which the first octet of each label contains the label's length. rtsold(8) did not validate label lengths correctly and could overflow the destination buffer.
How severe is CVE-2020-25583?: CVE-2020-25583 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-2020-25583 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (71st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-25583?: CVE-2020-25583 primarily affects Freebsd. In total, 29 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2020-25583?: 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-2020-25583 published?: CVE-2020-25583 was published on 2021-03-29 and last updated on 2026-06-17.

References

Affected products (29)

cpe:2.3:o:freebsd:freebsd:11.3:-:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:11.3:p1:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:11.3:p10:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:11.3:p11:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:11.3:p12:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:11.3:p13:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:11.3:p2:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:11.3:p3:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:11.3:p4:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:11.3:p5:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:11.3:p6:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:11.3:p7:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:11.3:p8:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:11.3:p9:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:11.4:-:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:11.4:p1:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:11.4:p2:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:11.4:p3:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:12.1:-:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:12.1:p1:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:12.1:p2:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:12.1:p3:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:12.1:p4:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:12.1:p5:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:12.1:p6:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:12.1:p7:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:12.1:p8:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:12.1:p9:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:12.2:-:*:*:*:*:*:*

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