Is CVE-2025-66220 in the CISA KEV catalog?

No. CVE-2025-66220 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2025-66220?

CVE-2025-66220 has a CVSS v3 base score of 5.0 (MEDIUM).

What is the EPSS score for CVE-2025-66220?

CVE-2025-66220 has an EPSS score of 0.16% (5th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2025-66220?

Upgrade envoy to 1.36.3 or later.

CVE & CISA-KEV Catalog

CVE-2025-66220

MEDIUM

5.0

CVSS v3

NVD

Description

Envoy is a high-performance edge/middle/service proxy. In 1.33.12, 1.34.10, 1.35.6, 1.36.2, and earlier, Envoy’s mTLS certificate matcher for match_typed_subject_alt_names may incorrectly treat certificates containing an embedded null byte (\0) inside an OTHERNAME SAN value as valid matches.

CWE-170

How to fix

Remediation Available

envoyNVD

Affected:>= 1.36.0, < 1.36.3Fixed in:1.36.3CVE-2025-66220derived from NVD

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityHigh

Privileges RequiredHigh

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityLow

AvailabilityNone

CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:L/A:N

Exploit Intelligence

0.16%probability of exploitation in 30 days

5thpercentile

Low risk: more likely to be exploited than 5% of all known CVEs.

References

Exploit1

github.com

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-12-05.