CVE-2023-35944

Envoy vulnerable to incorrect handling of HTTP requests and responses with mixed case schemes

Severity Score

5.3

*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

*Multiple Sources

Exploited in Wild

*KEV

Decision

Attend

*SSVC

Descriptions

Envoy is an open source edge and service proxy designed for cloud-native applications. Envoy allows mixed-case schemes in HTTP/2, however, some internal scheme checks are case-sensitive. Prior to versions 1.27.0, 1.26.4, 1.25.9, 1.24.10, and 1.23.12, this can lead to the rejection of requests with mixed-case schemes such as `htTp` or `htTps`, or the bypassing of some requests such as `https` in unencrypted connections. With a fix in versions 1.27.0, 1.26.4, 1.25.9, 1.24.10, and 1.23.12, Envoy will now lowercase scheme values by default, and change the internal scheme checks that were case-sensitive to be case-insensitive. There are no known workarounds for this issue.

A flaw was found in Envoy that allows for mixed-case schemes in HTTP/2. However, some internal scheme checks in Envoy are case-sensitive, leading to incorrect handling of requests and responses with mixed case schemes. For example, if a request with a mixed scheme HTTP is sent to the OAuth2 filter, it will fail the exact-match checks for HTTP and inform the remote endpoint the scheme is HTTP, thus potentially bypassing OAuth2 checks specific to HTTP requests.

Red Hat OpenShift Service Mesh is Red Hat's distribution of the Istio service mesh project, tailored for installation into an on-premise OpenShift Container Platform installation. Issues addressed include a memory leak vulnerability.

*Credits: N/A

CVSS Scores

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

Low

Availability

None

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

Low

Availability

None

Attack Vector

Network

Attack Complexity

Low

Authentication

None

Confidentiality

None

Integrity

Partial

Availability

None

* Common Vulnerability Scoring System

SSVC

Decision:Attend

Exploitation

Poc

Automatable

Tech. Impact

Total

* Organization's Worst-case Scenario

Timeline

2023-06-20 CVE Reserved
2023-07-25 CVE Published
2024-10-23 CVE Updated
2024-10-23 First Exploit
2025-03-30 EPSS Updated
---------- Exploited in Wild
---------- KEV Due Date

CWE

CWE-20: Improper Input Validation
CWE-178: Improper Handling of Case Sensitivity
CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

CAPEC

References (3)

URL	Tag	Source

URL	Date	SRC
https://github.com/envoyproxy/envoy/security/advisories/GHSA-pvgm-7jpg-pw5g	2024-10-23

URL	Date	SRC

URL	Date	SRC
https://access.redhat.com/security/cve/CVE-2023-35944	2023-09-14
https://bugzilla.redhat.com/show_bug.cgi?id=2217985	2023-09-14

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"				>= 1.23.0 < 1.23.12 Search vendor "Envoyproxy" for product "Envoy" and version " >= 1.23.0 < 1.23.12"		-		Affected
Envoyproxy Search vendor "Envoyproxy"		Envoy Search vendor "Envoyproxy" for product "Envoy"				>= 1.24.0 < 1.24.10 Search vendor "Envoyproxy" for product "Envoy" and version " >= 1.24.0 < 1.24.10"		-		Affected
Envoyproxy Search vendor "Envoyproxy"		Envoy Search vendor "Envoyproxy" for product "Envoy"				>= 1.25.0 < 1.25.9 Search vendor "Envoyproxy" for product "Envoy" and version " >= 1.25.0 < 1.25.9"		-		Affected
Envoyproxy Search vendor "Envoyproxy"		Envoy Search vendor "Envoyproxy" for product "Envoy"				>= 1.26.0 < 1.26.4 Search vendor "Envoyproxy" for product "Envoy" and version " >= 1.26.0 < 1.26.4"		-		Affected