Description
GnuTLS 3.6.x before 3.6.14 uses incorrect cryptography for encrypting a session ticket (a loss of confidentiality in TLS 1.2, and an authentication bypass in TLS 1.3). The earliest affected version is 3.6.4 (2018-09-24) because of an error in a 2018-09-18 commit. Until the first key rotation, the TLS server always uses wrong data in place of an encryption key derived from an application.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | gnutls28 | 3.6.14-1 | — |
| Debian 13 | gnutls28 | 3.6.14-1 | — |
| Debian 12 | gnutls28 | 3.6.14-1 | — |
| Debian 10 | gnutls28 | 3.6.7-4+deb10u4 | DSA-4697-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 20.04 LTS | gnutls28 | 3.6.13-2ubuntu1.1 | USN-4384-1 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 8 | gnutls +4 | 3.6.8-11.el8_2 | RHSA-2020:2637 |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 8.1 EUS | gnutls +4 | 3.6.8-9.el8_1 | RHSA-2020:2638 |
| RHEL 8.0 E4S | gnutls +4 | 3.6.5-3.el8_0 | RHSA-2020:2639 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP1 | gnutls | 3.6.7-6.29.1 | SUSE-SU-2020:1584-1 |
| SLES 15 | gnutls | 3.6.7-6.29.1 | SUSE-SU-2020:1584-1 |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 15 | gnutls | 3.6.7-6.29.1 | SUSE-SU-2020:1584-1 |
| SLE HPC 15 | gnutls | 3.6.7-6.29.1 | SUSE-SU-2020:1584-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | gnutls | 3.7.2-1.2 | openSUSE-SU-2024:10801-1 |
| openSUSE Leap 15.1 | gnutls | 3.6.7-lp151.2.18.1 | openSUSE-SU-2020:0790-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | gnutls | 3.6.14-r0 | — |
| Alpine v3.23 | gnutls | 3.6.14-r0 | — |
| Alpine v3.22 | gnutls | 3.6.14-r0 | — |
| Alpine v3.21 | gnutls | 3.6.14-r0 | — |
| Alpine v3.20 | gnutls | 3.6.14-r0 | — |
Show 11 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | gnutls | 3.6.14-r0 | — |
| Alpine v3.18 | gnutls | 3.6.14-r0 | — |
| Alpine v3.17 | gnutls | 3.6.14-r0 | — |
| Alpine v3.16 | gnutls | 3.6.14-r0 | — |
| Alpine v3.15 | gnutls | 3.6.14-r0 | — |
| Alpine v3.14 | gnutls | 3.6.14-r0 | — |
| Alpine v3.13 | gnutls | 3.6.14-r0 | — |
| Alpine v3.12 | gnutls | 3.6.14-r0 | — |
| Alpine v3.10 | gnutls | 3.6.14-r0 | — |
| Alpine v3.9 | gnutls | 3.6.14-r0 | — |
| Alpine v3.8 | gnutls | 3.6.14-r0 | — |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 8 | gnutls +4 | 3.6.8-11.el8_2 | ELSA-2020-2637 |
Public exploits
Exploit or proof-of-concept code for this vulnerability is publicly available, which lowers the bar for attackers. Treat it as a reason to patch sooner.
Third-party code, not reviewed by us. Public PoCs are sometimes fake or contain malware. Read the code first and run it only in an isolated lab, against systems you are authorised to test.
GitHub 3 repositories
-
0xxon/cve-2020-13777 ★ 4 · Jun 9, 2020
Zeek script to detect servers vulnerable to CVE-2020-13777
-
shigeki/challenge_CVE-2020-13777 ★ 2 · Jun 12, 2020
Challange CVE-2020-13777
-
prprhyt/PoC_TLS1_3_CVE-2020-13777 ★ 0 · Jun 21, 2020
Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.
Advisories 13
- RHSA-2020:2639 Red Hat Security Advisory: gnutls security update Red Hat Security Advisories (RHSA) · Oct 15, 2026
- RHSA-2020:2638 Red Hat Security Advisory: gnutls security update Red Hat Security Advisories (RHSA) · Oct 15, 2026
- RHSA-2020:2637 Red Hat Security Advisory: gnutls security update Red Hat Security Advisories (RHSA) · Oct 15, 2026
- SSA-398330 SSA-398330: Vulnerabilities in the additional GNU/Linux subsystem of the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP >= V3.1.0 and < V3.1.5 Siemens ProductCERT · Oct 13, 2026
- WID-SEC-2026-3124 GnuTLS: Schwachstelle ermöglicht Umgehen von Sicherheitsvorkehrungen BSI CERT-Bund (WID) · Aug 31, 2026
- WID-SEC-2025-0227 IBM QRadar SIEM: Mehrere Schwachstellen BSI CERT-Bund (WID) · Aug 11, 2026
- USN-4384-1 gnutls28 vulnerability Ubuntu Security Notices (USN) · Apr 22, 2026
- DSA-4697-1 gnutls28 - security update Debian Security (DSA / DLA) · Mar 9, 2026
- openSUSE-SU-2024:10801-1 gnutls-3.7.2-1.2 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2020:1584-1 Security update for gnutls SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2020:0790-1 Security update for gnutls SUSE / openSUSE Security Updates · Feb 4, 2026
- ICSA-23-348-10 Siemens SIMATIC S7-1500 CISA ICS & IT advisories · Aug 12, 2025
- ELSA-2020-2637 Important: gnutls security update (Oracle Linux 8) Oracle Linux Security Advisories (ELSA) · Jun 22, 2020
References
- https://gnutls.org/security-new.html#GNUTLS-SA-2020-06-03
- DSA-4697 vendor-advisory
- FEDORA-2020-0cce3578e2 vendor-advisory
- GLSA-202006-01 vendor-advisory
- USN-4384-1 vendor-advisory
- openSUSE-SU-2020:0790 vendor-advisory
- FEDORA-2020-76b705bb63 vendor-advisory
- FEDORA-2020-ea11cb5ccc vendor-advisory
- FEDORA-2020-4f78f122a3 vendor-advisory
- https://security.netapp.com/advisory/ntap-20200619-0004/