8.2

CVE-2026-26308: envoyproxy envoy Incorrect Authorization

CVSS: 8.2v3.1HighAnalyzed
AliasesGHSA-ghc4-35x6-crw5BIT-envoy-2026-26308
Published 10-03-2026Last modified 10-03-2026
Open JSON

Vulnerability summary

CVE-2026-26308 is a high (CVSS 8.2) Incorrect Authorization vulnerability in envoyproxy envoy. EPSS estimates a 0.36% chance of exploitation in the next 30 days, higher than 28.2% of scored vulnerabilities. 1 public exploit is recorded.

Overall risk
43/100
0100
Medium · default modelHow is this calculated?
CVSS score
8.2/10
010
High · v3.1 (NVD)
EPSS score
0.36%
0%100%
Low · +0.07 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits1github

Timeline

  1. 10-03-2026
    PublishedVulnerability first disclosed.
  2. 10-03-2026
    Last modifiedVulnerability information updated.

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 metrics

3 scores · 3 sources · 1 version

EPSS trend

Probability

0.36%

Chance of exploitation in the next 30 days

Percentile

28%

Versus all other CVEs

30-day change

+0.07 pp

From 0.29% on 21-09-2026

21-09-202621-10-2026
EPSS score
0.36%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

1 found
  • githubUnverified

    Envoy

    Maturity: poc

Weaknesses

CWE · root cause

Affected systems

Envoyproxy1 product
  • envoy≥ 1.37.0, < 1.37.1 | ≥ 1.35.0, < 1.35.9 | < 1.34.13 | ≥ 1.35.0, < 1.35.8 | ≥ 1.36.0, < 1.36.5 | 1.37.0
Github.com/envoyproxy1 product
  • envoy≥ 1.37.0, < 1.37.1 | ≥ 1.36.0, < 1.36.5 | ≥ 1.35.0, < 1.35.9 | < 1.34.13

2 vendors · 2 products

References

4 links