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CVE-2019-9901

28
FAUCET Score

CVE-2019-9901 is a critical vulnerability affecting Envoy proxy versions 1.9.0 and earlier, where improper URL path normalization allows attackers to bypass access controls. With a CVSS score of 10.0, this flaw enables remote attackers to craft relative paths (e.g., "something/../admin") to access restricted backend resources, leading to full compromise of confidentiality, integrity, and availability. Despite its critical severity, there is currently no known active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage surrounding this vulnerability.

Impacted Technologies

VendorProductVersion(s)CPE
<= 1.9.0CPE matchmatch criteria
cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

6.5MEDIUM

CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:L

Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
LOW
Integrity Impact
LOW
Availability Impact
LOW
Exploitability Score
2.2
Impact Score
3.7
CvssVersion
3.0

Exploit Intelligence

EPSS Score
2.68%
Probability of exploitation in next 30 days
EPSS Percentile
84.2%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0268 is in the 75th percentile among its peer group of 36,897 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (3)

gopatch availablevia ghsa
Product: github.com/envoyproxy/envoyFixed in: 1.9.1
redhatpatch availablevia redhat_api
Product: OpenShift Service Mesh Tech PreviewFixed in: servicemesh-proxy-0:0.9.1-1.el7
View patch
github_advisoryworkaround availablevia nvd_reference
View patch

Vendor Advisories (2)

goGHSA-2wmf-p7f8-w42hcritical

EnvoyProxy Envoy Missing HTTP URL path normalization

May 24, 2022
redhatCVE-2019-9901Important

istio/envoy: Path traversal via URL Patch manipulation in HTTP/1.x header

Apr 5, 2019

References

github.com / envoyproxy/envoy/issues/6435
Issue TrackingMitigationThird Party Advisory
github.com / envoyproxy/envoy/security/advisories/GHSA-xcx5-93pw-jw2w
groups.google.com / forum
envoyproxy.io / docs/envoy/v1.9.1/intro/version_history
Release NotesVendor Advisory