CVE-2025-66220
published 2025-12-03CVE-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…
PriorityP336high7.1CVSS 3.1
AVNACLPRLUINSUCHILAN
EPSS
0.16%
5.3th percentile
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.
Affected
12 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| envoyproxy | envoy | < 1.33.13 | 1.33.13 |
| envoyproxy | envoy | <= 1.33.12 | — |
| envoyproxy | envoy | — | — |
| envoyproxy | envoy | — | — |
| envoyproxy | envoy | — | — |
| envoyproxy | envoy | >= 1.34.0 < 1.34.11 | 1.34.11 |
| envoyproxy | envoy | >= 1.35.0 < 1.35.7 | 1.35.7 |
| envoyproxy | envoy | >= 1.36.0 < 1.36.3 | 1.36.3 |
| github.com | envoyproxy_envoy | >= 0 < 1.33.13 | 1.33.13 |
| github.com | envoyproxy_envoy | >= 1.34.0 < 1.34.11 | 1.34.11 |
| github.com | envoyproxy_envoy | >= 1.35.0 < 1.35.7 | 1.35.7 |
| github.com | envoyproxy_envoy | >= 1.36.0 < 1.36.3 | 1.36.3 |
CVSS provenance
nvdv3.17.1HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N
vendor_redhat5.0MEDIUM
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OSV
Envoy's TLS certificate matcher for `match_typed_subject_alt_names` may incorrectly treat certificates containing an embedded null byte
osv·2025-12-05
CVE-2025-66220 [MEDIUM] Envoy's TLS certificate matcher for `match_typed_subject_alt_names` may incorrectly treat certificates containing an embedded null byte
Envoy's TLS certificate matcher for `match_typed_subject_alt_names` may incorrectly treat certificates containing an embedded null byte
### Summary
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.
### Details
This occurs when the SAN is encoded as a `BMPSTRING` or `UNIVERSALSTRING`, and its UTF-8 conversion result is truncated at the first null byte during string assignment. As a result, `"victim\0evil"` may match an exact: `"victim"` rule and be accepted by Envoy.
### PoC
Create a CA and a server certificate signed by that CA.
Create two client certificates signed by the same CA:
client_evil with OTHERNAME BMPSTRING = "evil"
client_null with OT
GHSA
Envoy's TLS certificate matcher for `match_typed_subject_alt_names` may incorrectly treat certificates containing an embedded null byte
ghsa·2025-12-05
CVE-2025-66220 [MEDIUM] CWE-170 Envoy's TLS certificate matcher for `match_typed_subject_alt_names` may incorrectly treat certificates containing an embedded null byte
Envoy's TLS certificate matcher for `match_typed_subject_alt_names` may incorrectly treat certificates containing an embedded null byte
### Summary
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.
### Details
This occurs when the SAN is encoded as a `BMPSTRING` or `UNIVERSALSTRING`, and its UTF-8 conversion result is truncated at the first null byte during string assignment. As a result, `"victim\0evil"` may match an exact: `"victim"` rule and be accepted by Envoy.
### PoC
Create a CA and a server certificate signed by that CA.
Create two client certificates signed by the same CA:
client_evil with OTHERNAME BMPSTRING = "evil"
client_null with OT
Red Hat
envoy: Envoy: mTLS certificate validation bypass via embedded null byte in SAN
vendor_redhat·2025-12-03·CVSS 5.0
CVE-2025-66220 [MEDIUM] CWE-170 envoy: Envoy: mTLS certificate validation bypass via embedded null byte in SAN
envoy: Envoy: mTLS certificate validation bypass via embedded null byte in SAN
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.
A flaw was found in Envoy. This vulnerability allows mTLS (mutual Transport Layer Security) certificate validation bypass via a certificate containing an embedded null byte (\0) inside an OTHERNAME SAN (Subject Alternative Name) value.
Statement: This vulnerability is rated Moderate for Red Hat products. Envoy's mTLS certificate matcher, when configured with `match_typed_subject_alt_names`, may incorrectly validate certif
No detection rules found.
No public exploits indexed.
No writeups or analysis indexed.
2025-12-03
Published