CVE-2026-47778

What it is

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.

At a glance

Exploitability

Can be exploited over the network with an admin-level account. High risk of data exposure.

Exploit odds

0.2% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-06-26 18:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-10-25 17:10 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.2% in the next 30 days (EPSS).
• Severity: 4.4 MEDIUM (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2026-06-26 18:16 UTC

Last modified

2026-10-25 17:10 UTC

Exploit probability

0.2% · EPSS, next 30 days

Weakness

CWE-158

Record status

Analyzed

Affected

• Envoyproxy Envoy < 1.35.13
• Envoyproxy Envoy < 1.36.9
• Envoyproxy Envoy < 1.37.5
• Envoyproxy Envoy < 1.38.3

Attack profile CVSS 3.1 · 4.4

Attack vector

Network

Complexity

High

Privileges needed

High

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

None

Availability

None

Is it in your code?

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Read https://cve-list.com/agent/cve/CVE-2026-47778.md and follow it. Check whether this project is affected by CVE-2026-47778. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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