Skip to content
Fencer Vulns
high 7.4

CVE-2020-11501 json

GnuTLS 3.6.x before 3.6.13 uses incorrect cryptography for DTLS.

published 2020-04-03 6 y ago modified 2026-10-14 26 d ago also EUVD-2020-3854

cvss
7.4
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
3.4%
EPSS 3.4% chance of exploitation in 30 days, percentile 88%
public exploits
0
none known

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 thus contributes no randomness to a DTLS negotiation. This breaks the security guarantees of the DTLS protocol.

Patch / fix

  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP V3.1.5
  • Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP V3.1.5
  • Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP V3.1.5
  • gnutls28 Debian 14, Debian 13, Debian 12 3.6.13-2

debian advisories DEBIAN-CVE-2020-11501

  • gnutls RHEL 8 3.6.8-10.el8_2
  • gnutls-c++ RHEL 8 3.6.8-10.el8_2
  • gnutls-dane RHEL 8 3.6.8-10.el8_2
  • gnutls-utils RHEL 8 3.6.8-10.el8_2

red hat advisories RHSA-2020:1998

  • libnettle SLE Module for Certifications 15 SP3, SLE Module for Basesystem 15 SP1, SLE High Performance Computing 15-ESPOS +3 more 3.4.1-4.12.1
  • gmp SLE Module for Development Tools 15 SP1, SLE Module for Certifications 15 SP3, SLE Module for Basesystem 15 SP1 +4 more 6.1.2-4.3.1
  • gnutls SLES for SAP 15, SLES 15-LTSS, SLE Module for Basesystem 15 SP1 +2 more 3.6.7-6.14.1

suse advisories SUSE-SU-2020:0948-2SUSE-SU-2020:0948-1

  • libnettle openSUSE Leap 15.1 3.4.1-lp151.2.3.2
  • gmp openSUSE Leap 15.1 6.1.2-lp151.4.3.1
  • gnutls openSUSE Leap 15.1 3.6.7-lp151.2.6.1

opensuse advisories openSUSE-SU-2020:0501-1

  • gnutls Alpine 3.10 3.6.8-r1
  • gnutls Alpine 3.24, Alpine 3.23, Alpine 3.22 +10 more 3.6.13-r0
  • gnutls Alpine 3.9, Alpine 3.8 3.6.7-r1

alpine advisories ALPINE-CVE-2020-11501

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2020-11501 updated cvss 7.4

gnutls: DTLS client hello contains a random value of all zeroes

  • Red Hat Enterprise Linux AppStream (v. 8) gnutls-c++ 3.6.8-10.el8_2, gnutls-dane 3.6.8-10.el8_2, gnutls-utils 3.6.8-10.el8_2 Red Hat Enterprise Linux BaseOS (v. 8) gnutls 3.6.8-10.el8_2
    fixed: vendor fix RHSA-2020:1998
  • Red Hat Enterprise Linux 5 gnutls Red Hat Enterprise Linux 6 gnutls, gnutls-guile, gnutls-utils Red Hat Enterprise Linux 7 gnutls, gnutls-c++, gnutls-dane, gnutls-utils
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

cisa ICSA-23-348-10 updated cvss 7.4

Siemens SIMATIC S7-1500

  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) >= 3.1.0, < 3.1.5 Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) >= 3.1.0, < 3.1.5 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) >= 3.1.0, < 3.1.5 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) >= 3.1.0, < 3.1.5 Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) >= 3.1.0, < 3.1.5
    affected: fixed in V3.1.5, mitigation support.industry.siemens.com

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

Exploit prediction

3.39% chance of exploitation in the next 30 days, higher than 88% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 7.4 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
NVD 2.0 5.8 AV:N/AC:M/Au:N/C:P/I:P/A:N

Affected products

  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP
  • Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP
  • Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP

Classification

Weakness
  • CWE-330 Use of Insufficiently Random Values

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.