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CVE-2026-26308

⚠️ high
🔍 Scan for this CVE
Summary

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

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 headers, effectively obscuring the malicious value from exact-match mechanisms. This vulnerability is fixed in 1.37.1, 1.36.5, 1.35.8, and 1.34.13.

CVSS Score
7.5
High
EPSS Score
0.0
Published Date
2026-03-10
First Seen: 2026-03-11
📊 Relative Risk Intelligence

This CVE is Moderate Risk - more severe than 68.9% of all 330,245 vulnerabilities in our database.

#102,662
Above average severity
Severity Percentile
🎯 CISA SSVC Assessment Updated: Mar 10, 2026
🔍 Exploitation Status
None
No known exploits
⚙️ Automatable
NO
Requires human interaction
💥 Technical Impact
Partial
Limited system impact
SSVC data provided by CISA
Last Modified 2026-03-11
Source NVD 🔗
CVSS Vector 3.1 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:L/A:N
CWE IDs (Weakness Types)
CWE-863

📦 Affected Products 4

Vendor Product Status Affected Versions
envoyproxy envoy Affected
< 1.34.13
envoyproxy envoy Affected
> 1.35.0 < 1.35.8
envoyproxy envoy Affected
> 1.36.0 < 1.36.5
envoyproxy envoy Affected
v1.37.0

🔗 References 2

https://github.com/envoyproxy/envoy/commit/b6ba0b229...
Patch
https://github.com/envoyproxy/envoy/security/advisor...
Exploit Mitigation Vendor Advisory

🔗 Related CVEs 6

CVE ID Severity CVSS EPSS Summary Published
CVE-2026-47204 🔶 medium 6.5 0.4 Envoy is an open source edge and service proxy designed for cloud-native applications. From 1.26.0 until 1.35.13, 1.36.9... 2026-06-26
CVE-2026-47207 🔶 medium 6.5 0.4 Envoy is an open source edge and service proxy designed for cloud-native applications. From 1.34.0 until 1.35.13, 1.36.9... 2026-06-26
CVE-2026-47221 🔶 medium 5.9 0.4 Envoy is an open source edge and service proxy designed for cloud-native applications. From 1.18.0 until 1.35.13, 1.36.9... 2026-06-26
CVE-2026-47692 🔶 medium 4.8 0.2 Envoy is an open source edge and service proxy designed for cloud-native applications. From 1.34.0 until 1.35.13, 1.36.9... 2026-06-26
CVE-2026-26309 🔶 medium 5.3 0.0 Envoy is a high-performance edge/middle/service proxy. Prior to 1.37.1, 1.36.5, 1.35.8, and 1.34.13, an off-by-one write... 2026-03-10
CVE-2026-26310 🔶 medium 5.9 0.0 Envoy is a high-performance edge/middle/service proxy. Prior to 1.37.1, 1.36.5, 1.35.8, and 1.34.13, calling Utility::ge... 2026-03-10
These CVEs affect the same products