CVE-2021-32783 Vulnerability Analysis & Exploit Details

CVE-2021-32783
Vulnerability Scoring

8.5
/10
Severe Risk

Cybersecurity professionals consider CVE-2021-32783 an immediate threat requiring urgent mitigation.

Attack Complexity Details

  • Attack Complexity: Low
    Exploits can be performed without significant complexity or special conditions.
  • Attack Vector: Network
    Vulnerability is exploitable over a network without physical access.
  • Privileges Required: Low
    Some privileges are necessary to exploit the vulnerability.
  • Scope: Changed
    Successful exploitation can impact components beyond the vulnerable component.
  • User Interaction: None
    No user interaction is necessary for exploitation.

CVE-2021-32783 Details

Status: Modified

Last updated: 🕕 21 Nov 2024, 06:07 UTC
Originally published on: 🕙 23 Jul 2021, 22:15 UTC

Time between publication and last update: 1216 days

CVSS Release: version 3

CVSS3 Source

security-advisories@github.com

CVSS3 Type

Secondary

CVSS3 Vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:H

CVE-2021-32783 Vulnerability Summary

CVE-2021-32783: Contour is a Kubernetes ingress controller using Envoy proxy. In Contour before version 1.17.1 a specially crafted ExternalName type Service may be used to access Envoy's admin interface, which Contour normally prevents from access outside the Envoy container. This can be used to shut down Envoy remotely (a denial of service), or to expose the existence of any Secret that Envoy is using for its configuration, including most notably TLS Keypairs. However, it *cannot* be used to get the *content* of those secrets. Since this attack allows access to the administration interface, a variety of administration options are available, such as shutting down the Envoy or draining traffic. In general, the Envoy admin interface cannot easily be used for making changes to the cluster, in-flight requests, or backend services, but it could be used to shut down or drain Envoy, change traffic routing, or to retrieve secret metadata, as mentioned above. The issue will be addressed in Contour v1.18.0 and a cherry-picked patch release, v1.17.1, has been released to cover users who cannot upgrade at this time. For more details refer to the linked GitHub Security Advisory.

Assessing the Risk of CVE-2021-32783

Access Complexity Graph

The exploitability of CVE-2021-32783 depends on two key factors: attack complexity (the level of effort required to execute an exploit) and privileges required (the access level an attacker needs).

Exploitability Analysis for CVE-2021-32783

CVE-2021-32783 presents an accessible attack vector with minimal effort required. Restricting access controls and implementing security updates are critical to reducing exploitation risks.

Understanding AC and PR

A lower complexity and fewer privilege requirements make exploitation easier. Security teams should evaluate these aspects to determine the urgency of mitigation strategies, such as patch management and access control policies.

Attack Complexity (AC) measures the difficulty in executing an exploit. A high AC means that specific conditions must be met, making an attack more challenging, while a low AC means the vulnerability can be exploited with minimal effort.

Privileges Required (PR) determine the level of system access necessary for an attack. Vulnerabilities requiring no privileges are more accessible to attackers, whereas high privilege requirements limit exploitation to authorized users with elevated access.

CVSS Score Breakdown Chart

Above is the CVSS Sub-score Breakdown for CVE-2021-32783, illustrating how Base, Impact, and Exploitability factors combine to form the overall severity rating. A higher sub-score typically indicates a more severe or easier-to-exploit vulnerability.

CIA Impact Analysis

Below is the Impact Analysis for CVE-2021-32783, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.

  • Confidentiality: Low
    CVE-2021-32783 could lead to minor leaks of non-critical information without major privacy breaches.
  • Integrity: None
    CVE-2021-32783 poses no threat to data integrity.
  • Availability: High
    CVE-2021-32783 can disrupt system operations, potentially causing complete denial of service (DoS).

Exploit Prediction Scoring System (EPSS)

The EPSS score estimates the probability that this vulnerability will be exploited in the near future.

EPSS Score: 0.097% (probability of exploit)

EPSS Percentile: 42.66% (lower percentile = lower relative risk)
This vulnerability is less risky than approximately 57.34% of others.

CVE-2021-32783 References

External References

CWE Common Weakness Enumeration

CWE-610

CAPEC Common Attack Pattern Enumeration and Classification

  • XML Routing Detour Attacks CAPEC-219 An attacker subverts an intermediate system used to process XML content and forces the intermediate to modify and/or re-route the processing of the content. XML Routing Detour Attacks are Adversary in the Middle type attacks (CAPEC-94). The attacker compromises or inserts an intermediate system in the processing of the XML message. For example, WS-Routing can be used to specify a series of nodes or intermediaries through which content is passed. If any of the intermediate nodes in this route are compromised by an attacker they could be used for a routing detour attack. From the compromised system the attacker is able to route the XML process to other nodes of their choice and modify the responses so that the normal chain of processing is unaware of the interception. This system can forward the message to an outside entity and hide the forwarding and processing from the legitimate processing systems by altering the header information.

Vulnerable Configurations

  • cpe:2.3:a:projectcontour:contour:-:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:-:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:0.1.0:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:0.1.0:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:0.2.0:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:0.2.0:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:0.2.1:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:0.2.1:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:0.3.0:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:0.3.0:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:0.3.1:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:0.3.1:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:0.4.0:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:0.4.0:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:0.4.1:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:0.4.1:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:0.5.0:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:0.5.0:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:0.6.0:-:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:0.6.0:-:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:0.6.0:beta1:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:0.6.0:beta1:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:0.6.0:beta2:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:0.6.0:beta2:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:0.6.0:beta3:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:0.6.0:beta3:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:0.6.0:alpha1:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:0.6.0:alpha1:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:0.6.0:alpha2:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:0.6.0:alpha2:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:0.6.0:alpha3:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:0.6.0:alpha3:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:0.6.1:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:0.6.1:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:0.7.0:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:0.7.0:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:0.8.0:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:0.8.0:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:0.8.1:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:0.8.1:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:0.9.0:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:0.9.0:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:0.10.0:-:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:0.10.0:-:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:0.10.0:rc1:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:0.10.0:rc1:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:0.11.0:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:0.11.0:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:0.12.0:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:0.12.0:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:0.12.1:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:0.12.1:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:0.13.0:-:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:0.13.0:-:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:0.13.0:beta1:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:0.13.0:beta1:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:0.13.0:beta2:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:0.13.0:beta2:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:0.14.0:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:0.14.0:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:0.14.1:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:0.14.1:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:0.14.2:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:0.14.2:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:0.15.0:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:0.15.0:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:0.15.1:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:0.15.1:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:0.15.2:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:0.15.2:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:0.15.3:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:0.15.3:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:1.0.0:-:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:1.0.0:-:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:1.0.0:rc1:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:1.0.0:rc1:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:1.0.0:rc2:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:1.0.0:rc2:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:1.0.0:beta1:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:1.0.0:beta1:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:1.0.1:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:1.0.1:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:1.1.0:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:1.1.0:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:1.2.0:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:1.2.0:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:1.2.1:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:1.2.1:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:1.3.0:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:1.3.0:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:1.4.0:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:1.4.0:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:1.5.0:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:1.5.0:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:1.5.1:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:1.5.1:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:1.6.0:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:1.6.0:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:1.6.1:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:1.6.1:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:1.7.0:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:1.7.0:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:1.8.0:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:1.8.0:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:1.8.1:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:1.8.1:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:1.8.2:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:1.8.2:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:1.9.0:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:1.9.0:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:1.10.0:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:1.10.0:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:1.10.1:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:1.10.1:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:1.11.0:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:1.11.0:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:1.12.0:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:1.12.0:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:1.13.0:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:1.13.0:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:1.13.1:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:1.13.1:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:1.14.0:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:1.14.0:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:1.14.1:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:1.14.1:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:1.15.0:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:1.15.0:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:1.15.1:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:1.15.1:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:1.16.0:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:1.16.0:*:*:*:*:kubernetes:*:*
  • cpe:2.3:a:projectcontour:contour:1.17.0:*:*:*:*:kubernetes:*:*
    cpe:2.3:a:projectcontour:contour:1.17.0:*:*:*:*:kubernetes:*:*

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