---
id: CVE-2021-20231
title: A flaw was found in gnutls
summary: >-
  A flaw was found in gnutls. A use after free issue in client sending key_share
  extension may lead to memory corruption and other consequences.
severity: critical
cvss: 9.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-416
vendor: gnu
product: gnutls
affected:
  - 'gnutls >= 3.6.3, < 3.7.1'
  - enterprise_linux = 8.0
  - fedora = 34
  - active_iq_unified_manager
  - e-series_performance_analyzer
patched:
  - gnutls 3.7.1
published: '2021-03-12'
updated: '2026-10-14'
sourceUpdated: '2026-10-14T11:16:51.423'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2021-20231'
references:
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=1922276'
    label: secalert@redhat.com
  - url: >-
      https://lists.apache.org/thread.html/r50661d6f0082709aad9a584431b59ec364f9974b63b07e0800230168%40%3Cissues.spark.apache.org%3E
    label: secalert@redhat.com
  - url: >-
      https://lists.apache.org/thread.html/r5d4001031e7790d8c6396c499522b4ed2aab782da87b1a14184793bb%40%3Cissues.spark.apache.org%3E
    label: secalert@redhat.com
  - url: >-
      https://lists.apache.org/thread.html/r5f88bed447742fcc5c47bf1c7be965ef450131914a6e1f85feba2779%40%3Cissues.spark.apache.org%3E
    label: secalert@redhat.com
  - url: >-
      https://lists.apache.org/thread.html/r6ac143ba6dd98bd4bf6bf010d46e56e254056459721ba18822d611f7%40%3Cissues.spark.apache.org%3E
    label: secalert@redhat.com
  - url: >-
      https://lists.apache.org/thread.html/r9cbc69e57276413788e90a6ee16c7c034ea4258d31935b70db2bd158%40%3Cissues.spark.apache.org%3E
    label: secalert@redhat.com
  - url: >-
      https://lists.apache.org/thread.html/rcd70a4c88a47a75fd2d5f3ffb7cee8c2a18c713320bd90fdcb57495f%40%3Cissues.spark.apache.org%3E
    label: secalert@redhat.com
  - url: >-
      https://lists.apache.org/thread.html/rf5e1256d870193def4a82ad89ab95e63943a313b5ff0d81aa87e4532%40%3Cissues.spark.apache.org%3E
    label: secalert@redhat.com
  - url: >-
      https://lists.apache.org/thread.html/rfd5273d72d244178441e6904a2f2b41a3268f569e8092ea0b3b2bb20%40%3Cissues.spark.apache.org%3E
    label: secalert@redhat.com
  - url: >-
      https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/OSLAE6PP33A7VYRYMYMUVB3U6B26GZER/
    label: secalert@redhat.com
  - url: 'https://security.netapp.com/advisory/ntap-20210416-0005/'
    label: secalert@redhat.com
  - url: 'https://www.gnutls.org/security-new.html#GNUTLS-SA-2021-03-10'
    label: secalert@redhat.com
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=1922276'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://lists.apache.org/thread.html/r50661d6f0082709aad9a584431b59ec364f9974b63b07e0800230168%40%3Cissues.spark.apache.org%3E
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://lists.apache.org/thread.html/r5d4001031e7790d8c6396c499522b4ed2aab782da87b1a14184793bb%40%3Cissues.spark.apache.org%3E
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://lists.apache.org/thread.html/r5f88bed447742fcc5c47bf1c7be965ef450131914a6e1f85feba2779%40%3Cissues.spark.apache.org%3E
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://lists.apache.org/thread.html/r6ac143ba6dd98bd4bf6bf010d46e56e254056459721ba18822d611f7%40%3Cissues.spark.apache.org%3E
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://lists.apache.org/thread.html/r9cbc69e57276413788e90a6ee16c7c034ea4258d31935b70db2bd158%40%3Cissues.spark.apache.org%3E
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://lists.apache.org/thread.html/rcd70a4c88a47a75fd2d5f3ffb7cee8c2a18c713320bd90fdcb57495f%40%3Cissues.spark.apache.org%3E
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://lists.apache.org/thread.html/rf5e1256d870193def4a82ad89ab95e63943a313b5ff0d81aa87e4532%40%3Cissues.spark.apache.org%3E
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://lists.apache.org/thread.html/rfd5273d72d244178441e6904a2f2b41a3268f569e8092ea0b3b2bb20%40%3Cissues.spark.apache.org%3E
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/OSLAE6PP33A7VYRYMYMUVB3U6B26GZER/
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://security.netapp.com/advisory/ntap-20210416-0005/'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://www.gnutls.org/security-new.html#GNUTLS-SA-2021-03-10'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-398330.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
epss: 0.03751
epssPercentile: 0.89646
ingestedAt: '2026-10-14T11:27:22.120Z'
---

## Overview

A flaw was found in gnutls. A use after free issue in client sending key_share extension may lead to memory corruption and other consequences.

## Affected

- `gnutls >= 3.6.3, < 3.7.1`
- `enterprise_linux = 8.0`
- `fedora = 34`
- `active_iq_unified_manager`
- `e-series_performance_analyzer`

## Remediation

Upgrade past the affected range:

- `gnutls 3.7.1`