CVE-2026-26308 — Incorrect Authorization in Envoy

CWE-863 — Incorrect AuthorizationCWE-20 — Improper Input Validation9 documents5 sources
Severity
8.2HIGHNVD
CNA7.5
EPSS
0.0%
top 99.94%
CISA KEV
Not in KEV
Exploit
No known exploits
Affected products
2
Envoyproxy EnvoyGithub.com Envoyproxy Envoy
Timeline
PublishedMar 10

Description

Envoy is a high-performance edge/middle/service proxy. Prior to 1.37.1, 1.36.5, 1.35.8, and 1.34.13, the Envoy RBAC (Role-Based Access Control) filter contains a logic vulnerability in how it validates HTTP headers when multiple values are present for the same header name. Instead of validating each header value individually, Envoy concatenates all values into a single comma-separated string. This behavior allows attackers to bypass RBAC policies—specifically "Deny" rules—by sending duplicate he…

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:NExploitability: 3.9 | Impact: 4.2

Affected Packages3 packages

▶CVEListV5envoyproxy/envoy< 1.34.13+3
▶NVDenvoyproxy/envoy1.35.0 — 1.35.8+3
▶Gogithub.com/envoyproxy_envoy1.37.0 — 1.37.1+6

Patches

Patch: github.com ↗

🔴Vulnerability Details

3
CVEList
Envoy has an RBAC Header Validation Bypass via Multi-Value Header Concatenation↗2026-03-10
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GHSA
Envoy has RBAC Header Validation Bypass via Multi-Value Header Concatenation↗2026-03-10
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OSV
Envoy has RBAC Header Validation Bypass via Multi-Value Header Concatenation↗2026-03-10
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🕵️Threat Intelligence

5
Wiz
CVE-2026-26308 Impact, Exploitability, and Mitigation Steps | Wiz↗
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Wiz
CVE-2026-26310 Impact, Exploitability, and Mitigation Steps | Wiz↗
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Wiz
CVE-2026-26311 Impact, Exploitability, and Mitigation Steps | Wiz↗
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Wiz
CVE-2026-26309 Impact, Exploitability, and Mitigation Steps | Wiz↗
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Wiz
CVE-2026-26330 Impact, Exploitability, and Mitigation Steps | Wiz↗
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