Answer in brief
CVE-2026-47778 records a Medium severity (CVSS 4.4) vulnerability in Envoy: Embedded NUL in TLS DNS SAN Truncation in the Default TLS Certificate Validator. (Auth Bypass). The current sources do not mark it as known exploited. The current feed maps envoyproxy/envoy (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 4.4. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps envoyproxy/envoy (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| envoyproxy/envoygeneric | >= 1.38.0, < 1.38.1 || >= 1.37.0, < 1.37.3 || >= 1.36.0, < 1.36.7 || < 1.35.11 | Not reported |
Published upstream
Jun 26, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Jun 29, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Jun 26, 2026
Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to 1.35.11, 1.36.7, 1.37.3, and 1.38.1, a structural flaw was identified in DefaultCertValidator::verifySubjectAltName where the extracted DNS SAN string is cast to a C-style string using .c_str() before being passed to the Utility::dnsNameMatch() algorithm. If the attacker serves a certificate with a dNSName SAN containing an embedded NUL byte, the helper Utility::generalNameAsString captures the complete string including the NUL. However, when .c_str() evaluates it, implicit conversion to absl::string_view inside dnsNameMatch relies on strlen(), prematurely truncating the evaluation context. Envoy evaluates trucated string against the exact required config_san match and returns true, thereby successfully validating the string with the Nul byte for an upstream routing. This vulnerability is fixed in 1.35.11, 1.36.7, 1.37.3, and 1.38.1.
Quoted source text, attributed separately from HOL analysis.
Answer in brief
CVE-2026-47778 records a Medium severity (CVSS 4.4) vulnerability in Envoy: Embedded NUL in TLS DNS SAN Truncation in the Default TLS Certificate Validator. (Auth Bypass). The current sources do not mark it as known exploited. The current feed maps envoyproxy/envoy (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 4.4. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps envoyproxy/envoy (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| envoyproxy/envoygeneric | >= 1.38.0, < 1.38.1 || >= 1.37.0, < 1.37.3 || >= 1.36.0, < 1.36.7 || < 1.35.11 | Not reported |
Published upstream
Jun 26, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Jun 29, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Jun 26, 2026
Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to 1.35.11, 1.36.7, 1.37.3, and 1.38.1, a structural flaw was identified in DefaultCertValidator::verifySubjectAltName where the extracted DNS SAN string is cast to a C-style string using .c_str() before being passed to the Utility::dnsNameMatch() algorithm. If the attacker serves a certificate with a dNSName SAN containing an embedded NUL byte, the helper Utility::generalNameAsString captures the complete string including the NUL. However, when .c_str() evaluates it, implicit conversion to absl::string_view inside dnsNameMatch relies on strlen(), prematurely truncating the evaluation context. Envoy evaluates trucated string against the exact required config_san match and returns true, thereby successfully validating the string with the Nul byte for an upstream routing. This vulnerability is fixed in 1.35.11, 1.36.7, 1.37.3, and 1.38.1.
Quoted source text, attributed separately from HOL analysis.