How severe is CVE-2025-66220?

CVE-2025-66220 has a CVSS 3.x base score of 5.0, rated medium severity. It is exploitable over network with high attack complexity, requires high privileges and no user interaction. Impact on confidentiality is high, integrity low, and availability none.

Is CVE-2025-66220 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (6th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2025-66220?

CVE-2025-66220 affects Envoyproxy Envoy. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2025-66220?

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

Does CVE-2025-66220 have an EU (EUVD) identifier?

Yes. CVE-2025-66220 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-201090.

When was CVE-2025-66220 published?

CVE-2025-66220 was published on 2025-12-03 and last updated on 2026-06-17.

CVE-2025-66220

CVE-2025-66220 is a medium-severity vulnerability in Envoyproxy Envoy with a CVSS 3.x base score of 5.0. 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-170.

Key facts

Severity: Medium (CVSS 3.x base score 5.0)
EPSS exploit prediction: 0% (6th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-201090
Weakness: CWE-170
Affected product: Envoyproxy Envoy
Published: 2025-12-03
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2025-66220?: 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.
How severe is CVE-2025-66220?: CVE-2025-66220 has a CVSS 3.x base score of 5.0, rated medium severity. It is exploitable over network with high attack complexity, requires high privileges and no user interaction. Impact on confidentiality is high, integrity low, and availability none.
Is CVE-2025-66220 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (6th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-66220?: CVE-2025-66220 affects Envoyproxy Envoy. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2025-66220?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2025-66220 have an EU (EUVD) identifier?: Yes. CVE-2025-66220 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-201090.
When was CVE-2025-66220 published?: CVE-2025-66220 was published on 2025-12-03 and last updated on 2026-06-17.

References

https://github.com/envoyproxy/envoy/security/advisories/GHSA-rwjg-c3h2-f57p

Affected products (1)

cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*

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