CVE-2021-31920: Istio.io/istio Istio Authorization Bypass Vulnerability Vulnerability

Q: What is CVE-2021-31920?

CVE-2021-31920 is a security vulnerability in Istio.io/istio involving Istio Authorization Bypass Vulnerability under CWE-863: Incorrect Authorization.

Q: Which Istio.io/istio versions are affected?

Affected versions include releases prior to 1.8.6, 1.9.5 across affected packages: istio.io/istio.

Q: What version fixes CVE-2021-31920?

Upgrading to 1.8.6, 1.9.5 (or the latest patched release for your respective branch) resolves the vulnerability.

Q: Is istio.io/istio affected?

Yes, istio.io/istio is affected in releases prior to 1.8.6, 1.9.5. Upgrade your dependency to 1.8.6, 1.9.5 or later.

Q: What is the CVSS score of CVE-2021-31920?

CVE-2021-31920 has a CVSS v3.1 base score of 6.5 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N.

Q: What CWE is associated with CVE-2021-31920?

CVE-2021-31920 is classified under CWE-863: Incorrect Authorization (The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.).

Q: How can I check Go dependencies for CVE-2021-31920?

Run the dependency tree command: 'inspect dependencies for istio.io/istio'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.

MODERATE

Advisory Identifier: GHSA-6q5m-22mq-q2xv

CVSS 6.5

CWE-863

Published 2022-05-24

Advisory Summary

CVE-2021-31920 is a MODERATE (CVSS 6.5) istio authorization bypass vulnerability vulnerability (CWE-863: Incorrect Authorization) affecting Istio.io/istio libraries in the Go ecosystem. The issue involves istio authorization bypass vulnerability. Remediation is available by upgrading affected packages to version 1.8.6, 1.9.5.

CVE-2021-31920 at a Glance

CVE Identifier CVE-2021-31920

GHSA Identifier GHSA-6q5m-22mq-q2xv

Severity MODERATE

CVSS v3.1 Base Score 6.5

CWE Classification CWE-863: Incorrect Authorization

Affected Product Istio.io/istio

Package Ecosystem Go

Published Date 2022-05-24

Last Updated 2023-08-07

Security Impact

CVSS: 6.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N).

Attack Vector Network (AV:N)

Attack Complexity Low (AC:L)

Privileges Required Low (PR:L)

User Interaction None (UI:N)

Scope Unchanged (S:U)

Confidentiality High (C:H)

Integrity None (I:N)

Availability None (A:N)

How to Fix CVE-2021-31920

To remediate this vulnerability, upgrade all affected Istio.io/istio dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

istio.io/istio fixed: 1.8.6

Upgrade istio.io/istio to 1.8.6

istio.io/istio fixed: 1.9.5

Upgrade istio.io/istio to 1.9.5

Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release:

inspect dependencies for istio.io/istio

How to Check if You Are Affected

To determine whether your application is affected by CVE-2021-31920, inspect your project dependencies for Istio.io/istio:

inspect dependencies for istio.io/istio

Analyze the terminal output to locate any version of Istio.io/istio in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.8.6), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-863: Incorrect Authorization, where the product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check. In Istio.io/istio, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

Istio before 1.8.6 and 1.9.x before 1.9.5 has a remotely exploitable vulnerability where an HTTP request path with multiple slashes or escaped slash characters (%2F or %5C) could potentially bypass an Istio authorization policy when path based authorization rules are used.

CVE-2021-31920 Affected Istio.io/istio Versions

2 component(s)

Fixed Versions:

1.8.61.9.5

Product / Package	Ecosystem	Affected Versions	Fixed Version
istio.io/istio golang/istio.io/istio	Go	< 1.8.6	1.8.6
istio.io/istio golang/istio.io/istio	Go	≥ 1.9.0 < 1.9.5	1.9.5

References

NVD — CVE-2021-31920 NVD

https://nvd.nist.gov/vuln/detail/CVE-2021-31920

Istio.io/istio Security Information SECURITY

https://istio.io/latest/news/security/istio-security-2021-005

Frequently Asked Questions

What is CVE-2021-31920?

CVE-2021-31920 is a security vulnerability in Istio.io/istio involving Istio Authorization Bypass Vulnerability under CWE-863: Incorrect Authorization.

Which Istio.io/istio versions are affected?

Affected versions include releases prior to 1.8.6, 1.9.5 across affected packages: istio.io/istio.

What version fixes CVE-2021-31920?

Upgrading to 1.8.6, 1.9.5 (or the latest patched release for your respective branch) resolves the vulnerability.

Is istio.io/istio affected?

Yes, istio.io/istio is affected in releases prior to 1.8.6, 1.9.5. Upgrade your dependency to 1.8.6, 1.9.5 or later.

What is the CVSS score of CVE-2021-31920?

CVE-2021-31920 has a CVSS v3.1 base score of 6.5 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N.

What CWE is associated with CVE-2021-31920?

CVE-2021-31920 is classified under CWE-863: Incorrect Authorization (The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.).

How can I check Go dependencies for CVE-2021-31920?

Run the dependency tree command: 'inspect dependencies for istio.io/istio'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.

Machine-readable OSV JSON OSV v1.5 Schema

Normalized schema output

View Raw JSON

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-6q5m-22mq-q2xv",
  "modified" : "2023-08-07T20:57:01Z",
  "published" : "2022-05-24T19:03:32Z",
  "withdrawn" : "2023-08-07T20:57:01Z",
  "aliases" : [ "CVE-2021-31920" ],
  "summary" : "Istio Authorization Bypass Vulnerability",
  "details" : "Istio before 1.8.6 and 1.9.x before 1.9.5 has a remotely exploitable vulnerability where an HTTP request path with multiple slashes or escaped slash characters (%2F or %5C) could potentially bypass an Istio authorization policy when path based authorization rules are used.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "istio.io/istio"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.8.6"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Go",
      "name" : "istio.io/istio"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "1.9.0"
      }, {
        "fixed" : "1.9.5"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 1.9.4"
    }
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-31920"
  }, {
    "type" : "WEB",
    "url" : "https://istio.io/latest/news/security/istio-security-2021-005"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-863" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2023-07-11T16:53:41Z",
    "nvd_published_at" : "2021-05-27T05:15:00Z"
  }
}

CVSS V3

6.5 MODERATE