CVE-2021-28683

envoyproxy/envoy: NULL pointer dereference in TLS alert code handling

Severity Score

7.5

*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

*Multiple Sources

Exploited in Wild

*KEV

Decision

*SSVC

Descriptions

An issue was discovered in Envoy through 1.71.1. There is a remotely exploitable NULL pointer dereference and crash in TLS when an unknown TLS alert code is received.

Se detectó un problema en Envoy versiones hasta 1.71.1. Se presenta una desreferencia de puntero NULL explotable remoto y bloqueo en TLS cuando es recibido un código de alerta TLS desconocido

A NULL pointer dereference vulnerability was found envoyproxy/envoy. This flaw allows an attacker to establish a TLS session that sends an invalid TLS alert code, causing a NULL pointer exception to occur that crashes the application, resulting in a denial of service. The highest threat from this vulnerability is to system availability.

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 integer overflow and null pointer vulnerabilities.

*Credits: N/A

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Attack Vector

Network

Attack Complexity

Low

Authentication

None

Confidentiality

None

Integrity

None

Availability

Partial

* Common Vulnerability Scoring System

SSVC

Decision:-

Exploitation

Automatable

Tech. Impact

* Organization's Worst-case Scenario

Timeline

2021-03-18 CVE Reserved
2021-04-22 CVE Published
2024-08-03 CVE Updated
2025-03-30 EPSS Updated
---------- Exploited in Wild
---------- KEV Due Date
---------- First Exploit

CWE

CWE-476: NULL Pointer Dereference

CAPEC

References (6)

URL	Tag	Source
https://github.com/envoyproxy/envoy/releases	Third Party Advisory
https://github.com/envoyproxy/envoy/security/advisories/GHSA-r22g-5f3x-xjgg	Not Applicable
https://github.com/envoyproxy/envoy/security/advisories/GHSA-xw4q-6pj2-5gfg	Third Party Advisory

URL	Date	SRC

URL	Date	SRC

URL	Date	SRC
https://blog.envoyproxy.io	2021-05-27
https://access.redhat.com/security/cve/CVE-2021-28683	2021-04-22
https://bugzilla.redhat.com/show_bug.cgi?id=1942263	2021-04-22

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"				1.16.2 Search vendor "Envoyproxy" for product "Envoy" and version "1.16.2"		-		Affected
Envoyproxy Search vendor "Envoyproxy"		Envoy Search vendor "Envoyproxy" for product "Envoy"				1.17.1 Search vendor "Envoyproxy" for product "Envoy" and version "1.17.1"		-		Affected