CVE-2025-66220

Q: How do I fix CVE-2025-66220?

Upgrade envoy to 1.36.3 or later.

Q: Is CVE-2025-66220 being actively exploited?

Not that we know of. CVE-2025-66220 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.17% is the estimated probability that it will be exploited in the next 30 days. That is higher than 7% of all scored CVEs.

Q: How severe is CVE-2025-66220?

CVE-2025-66220 has a CVSS v3 base score of 5.0, rated medium. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

Q: What does CVE-2025-66220 affect?

Published advisories record a fix for envoy (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

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

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

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

0.17%probability of exploitation in 30 days

7thpercentile

Low risk: more likely to be exploited than 7% of all known CVEs.

References

Exploit1

github.com

Related Vulnerabilities

Other CWE-170 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2021-22931	Critical	9.8	22%	-	Fix
CVE-2019-11045	Low	3.7	8.8%	-	Fix
CVE-2019-11044	Low	3.7	5.1%	-	Fix
CVE-2019-8275	Critical	9.8	4.0%	-	Fix
CVE-2020-27736	Medium	6.5	3.6%	-	Fix
CVE-2021-31886	Critical	9.8	3.0%	-	Fix

Common questions

How do I fix CVE-2025-66220?

Upgrade envoy to 1.36.3 or later.

Is CVE-2025-66220 being actively exploited?

Not that we know of. CVE-2025-66220 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.17% is the estimated probability that it will be exploited in the next 30 days. That is higher than 7% of all scored CVEs.

How severe is CVE-2025-66220?

CVE-2025-66220 has a CVSS v3 base score of 5.0, rated medium. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

What does CVE-2025-66220 affect?

Published advisories record a fix for envoy (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

Embed a live status badge for CVE-2025-66220

Markdown

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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.