---
id: CVE-2020-11501
title: GnuTLS 3.6.x before 3.6.13 uses incorrect cryptography for DTLS
summary: >-
  GnuTLS 3.6.x before 3.6.13 uses incorrect cryptography for DTLS. The earliest
  affected version is 3.6.3 (2018-07-16) because of an error in a 2017-10-06
  commit. The DTLS client always uses 32 '\0' bytes instead of a random value,
  and thu…
severity: high
cvss: 7.4
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N'
cwe:
  - CWE-330
vendor: gnu
product: gnutls
affected:
  - 'gnutls >= 3.6.3, < 3.6.13'
  - ubuntu_linux = 19.10
  - debian_linux = 10.0
  - leap = 15.1
  - fedora = 31
  - fedora = 32
patched:
  - gnutls 3.6.13
published: '2020-04-03'
updated: '2026-10-14'
sourceUpdated: '2026-10-14T09:17:17.877'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2020-11501'
references:
  - url: 'http://lists.opensuse.org/opensuse-security-announce/2020-04/msg00015.html'
    label: cve@mitre.org
  - url: >-
      https://gitlab.com/gnutls/gnutls/-/commit/5b595e8e52653f6c5726a4cdd8fddeb6e83804d2
    label: cve@mitre.org
  - url: 'https://gitlab.com/gnutls/gnutls/-/issues/960'
    label: cve@mitre.org
  - url: >-
      https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ILMOWPKMTZAIMK5F32TUMO34XCABUCFJ/
    label: cve@mitre.org
  - url: >-
      https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WDYY3R4F5CUTFAMXH2C5NKYFVDEJLTT7/
    label: cve@mitre.org
  - url: 'https://security.gentoo.org/glsa/202004-06'
    label: cve@mitre.org
  - url: 'https://security.netapp.com/advisory/ntap-20200416-0002/'
    label: cve@mitre.org
  - url: 'https://usn.ubuntu.com/4322-1/'
    label: cve@mitre.org
  - url: 'https://www.debian.org/security/2020/dsa-4652'
    label: cve@mitre.org
  - url: 'https://www.gnutls.org/security-new.html#GNUTLS-SA-2020-03-31'
    label: cve@mitre.org
  - url: 'http://lists.opensuse.org/opensuse-security-announce/2020-04/msg00015.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://gitlab.com/gnutls/gnutls/-/commit/5b595e8e52653f6c5726a4cdd8fddeb6e83804d2
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://gitlab.com/gnutls/gnutls/-/issues/960'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ILMOWPKMTZAIMK5F32TUMO34XCABUCFJ/
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WDYY3R4F5CUTFAMXH2C5NKYFVDEJLTT7/
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://security.gentoo.org/glsa/202004-06'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://security.netapp.com/advisory/ntap-20200416-0002/'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://usn.ubuntu.com/4322-1/'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://www.debian.org/security/2020/dsa-4652'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://www.gnutls.org/security-new.html#GNUTLS-SA-2020-03-31'
    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
  - cve.org
epss: 0.03388
epssPercentile: 0.88528
ingestedAt: '2026-10-14T09:24:26.054Z'
---

## Overview

GnuTLS 3.6.x before 3.6.13 uses incorrect cryptography for DTLS. The earliest affected version is 3.6.3 (2018-07-16) because of an error in a 2017-10-06 commit. The DTLS client always uses 32 '\0' bytes instead of a random value, and thus contributes no randomness to a DTLS negotiation. This breaks the security guarantees of the DTLS protocol.

## Affected

- `gnutls >= 3.6.3, < 3.6.13`
- `ubuntu_linux = 19.10`
- `debian_linux = 10.0`
- `leap = 15.1`
- `fedora = 31`
- `fedora = 32`

## Remediation

Upgrade past the affected range:

- `gnutls 3.6.13`