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Fencer Vulns
medium 5.0

CVE-2025-66220 json

Envoy’s TLS certificate matcher for `match_typed_subject_alt_names` may incorrectly treat certificates containing an embedded null byte

published 2025-12-03 11 mo ago modified 2026-09-25 44 d ago also BIT-envoy-2025-66220 , EUVD-2025-201090 , GHSA-rwjg-c3h2-f57p

cvss
5.0
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 7%
public exploits
0
none known

Summary

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.

Patch / fix

  • go github.com/envoyproxy/envoy 1.33.13, 1.34.11, 1.35.7, 1.36.3
  • bitnami envoy 1.33.13, 1.34.11, 1.35.7, 1.36.3
  • envoyproxy envoy 1.33.13, 1.34.11, 1.35.7, 1.36.3

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2025-66220 updated cvss 5.0

envoy: Envoy: mTLS certificate validation bypass via embedded null byte in SAN

  • Red Hat OpenShift Service Mesh 3 openshift-service-mesh/istio-proxyv2-rhel9, openshift-service-mesh/istio-ztunnel-rhel9
    affected: workaround, no fix available
  • Red Hat OpenShift Service Mesh 2 openshift-service-mesh/pilot-rhel8, openshift-service-mesh/grafana-rhel8, openshift-service-mesh/proxyv2-rhel9, openshift-service-mesh/istio-cni-rhel8, openshift-service-mesh/ratelimit-rhel8, openshift-service-mesh/istio-rhel8-operator, +2 more Red Hat OpenShift Service Mesh 3 openshift-service-mesh/istio-cni-rhel9, openshift-service-mesh/istio-pilot-rhel9, openshift-service-mesh/istio-rhel9-operator, openshift-service-mesh/istio-must-gather-rhel9, openshift-service-mesh/istio-sail-operator-bundle, openshift-service-mesh-tech-preview/istio-ztunnel-rhel9, +1 more
    not affected: component not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
11 mo ago

Exploit prediction

0.18% chance of exploitation in the next 30 days, higher than 7% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/envoyproxy/envoy/security/advisories/GHSA-rwjg-c3h2-f57p referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 5.0 CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:L/A:N
GitHub 3.1 5.0 CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:L/A:N
NVD 3.1 7.1 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N
OSV 3.1 7.1 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N

Affected packages

ecosystem package affected fixed in
go github.com/envoyproxy/envoy
>=1.36.0, <1.36.3
>=1.35.0, <1.35.7
>=1.34.0, <1.34.11
<1.33.13
1.36.3
1.35.7
1.34.11
1.33.13
bitnami envoy
<1.33.13
>=1.34.0, <1.34.11
>=1.35.0, <1.35.7
>=1.36.0, <1.36.3
1.33.13
1.34.11
1.35.7
1.36.3

Affected products

  • envoyproxy envoy

Classification

Weakness
  • CWE-170 Improper Null Termination

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.