CVE-2023-27491

Envoy forwards invalid Http2/Http3 downstream headers

Severity Score

9.1

*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

*Multiple Sources

Exploited in Wild

*KEV

Decision

Track*

*SSVC

Descriptions

Envoy is an open source edge and service proxy designed for cloud-native applications. Compliant HTTP/1 service should reject malformed request lines. Prior to versions 1.26.0, 1.25.3, 1.24.4, 1.23.6, and 1.22.9, There is a possibility that non compliant HTTP/1 service may allow malformed requests, potentially leading to a bypass of security policies. This issue is fixed in versions 1.26.0, 1.25.3, 1.24.4, 1.23.6, and 1.22.9.

A flaw was found in Envoy that may allow attackers to send specially crafted HTTP/2 or HTTP/3 requests to trigger parsing errors on the upstream HTTP/1 service.

Red Hat OpenShift Service Mesh is Red Hat's distribution of the Istio service mesh project, tailored for installation into an OpenShift Container Platform installation.

*Credits: N/A

CVSS Scores

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

None

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Unchanged

Confidentiality

Low

Integrity

Low

Availability

None

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Attack Vector

Network

Attack Complexity

Low

Authentication

None

Confidentiality

Complete

Integrity

Complete

Availability

None

* Common Vulnerability Scoring System

SSVC

Decision:Track*

Exploitation

Poc

Automatable

Tech. Impact

Partial

* Organization's Worst-case Scenario

Timeline

2023-03-01 CVE Reserved
2023-04-04 CVE Published
2025-02-11 CVE Updated
2025-02-11 First Exploit
2025-03-30 EPSS Updated
---------- Exploited in Wild
---------- KEV Due Date

CWE

CWE-20: Improper Input Validation
CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

CAPEC

References (6)

URL	Tag	Source
https://datatracker.ietf.org/doc/html/rfc9113#section-8.3	Not Applicable
https://datatracker.ietf.org/doc/html/rfc9114#section-4.3.1	Not Applicable
https://www.rfc-editor.org/rfc/rfc9110#section-5.6.2	Not Applicable

URL	Date	SRC
https://github.com/envoyproxy/envoy/security/advisories/GHSA-5jmv-cw9p-f9rp	2025-02-11

URL	Date	SRC

URL	Date	SRC
https://access.redhat.com/security/cve/CVE-2023-27491	2023-08-11
https://bugzilla.redhat.com/show_bug.cgi?id=2179138	2023-08-11

Affected Vendors, Products, and Versions

Vendor		Product				Version		Other		Status
Vendor	Product	Version	Other	Status	<-- -->	Vendor	Product	Version	Other	Status
Envoyproxy Search vendor "Envoyproxy"		Envoy Search vendor "Envoyproxy" for product "Envoy"				< 1.22.9 Search vendor "Envoyproxy" for product "Envoy" and version " < 1.22.9"		-		Affected
Envoyproxy Search vendor "Envoyproxy"		Envoy Search vendor "Envoyproxy" for product "Envoy"				>= 1.23.0 < 1.23.6 Search vendor "Envoyproxy" for product "Envoy" and version " >= 1.23.0 < 1.23.6"		-		Affected
Envoyproxy Search vendor "Envoyproxy"		Envoy Search vendor "Envoyproxy" for product "Envoy"				>= 1.24.0 < 1.24.4 Search vendor "Envoyproxy" for product "Envoy" and version " >= 1.24.0 < 1.24.4"		-		Affected
Envoyproxy Search vendor "Envoyproxy"		Envoy Search vendor "Envoyproxy" for product "Envoy"				>= 1.25.0 < 1.25.3 Search vendor "Envoyproxy" for product "Envoy" and version " >= 1.25.0 < 1.25.3"		-		Affected