Reference page — cumulative record through Wednesday, August 19, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.
envoyproxy envoy — Envoy: Embedded NUL in TLS DNS SAN Truncation in the Default TLS Certificate Validator. (Auth Bypass)
AV AC PR UI S C I A CVSS EPSS %ile KEV
N H H N U H N N 4.4 .0018 7.5 —
AFFECTED
Product Versions Fixed
envoy >= 1.38.0, < 1.38.1 – —
TIMELINE
May 19 Reserved by GitHub_M
Jun 26 EXPLOIT PUBLISHED — CVE-2026-47778 (envoyproxy envoy). Public exploit reference added.
Jun 26 Published (CNA: GitHub_M)
Description
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.
Lifecycle
Complete event history — 3 events, chronological
| Date | Event | Detail |
|---|
| May 19, 2026 | Reserved | Reserved by GitHub_M |
| June 26, 2026 | EXPLOIT PUBLISHED | EXPLOIT PUBLISHED — CVE-2026-47778 (envoyproxy envoy). Public exploit reference added. |
| June 26, 2026 | Published | Published (CNA: GitHub_M) |
Affected
Affected products and packages — 1 row
| Vendor | Product / Package | Ecosystem | Version introduced | Fixed |
|---|
| envoyproxy | envoy | — | >= 1.38.0, < 1.38.1 | — |
About this page
This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2026-47778 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Wednesday, August 19, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.