Ubuntu update for GnuTLS

Published: 2020-06-10
Risk Medium
Patch available YES
Number of vulnerabilities 1
CVE ID CVE-2020-13777
Exploitation vector Local network
Public exploit Public exploit code for vulnerability #1 is available.
Vulnerable software
gnutls28 (Ubuntu package)
Operating systems & Components / Operating system package or component

Vendor Canonical Ltd.

Security Advisory

This security advisory describes one medium risk vulnerability.

1) Man-in-the-Middle (MitM) attack

Risk: Medium

CVSSv3.1: 5.5 [CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N/E:P/RL:O/RC:C] [PCI]

CVE-ID: CVE-2020-13777

CWE-ID: CWE-300 - Channel Accessible by Non-Endpoint ('Man-in-the-Middle')

Exploit availability: Yes


The vulnerability allows a remote attacker to perform Man-in-the-Middle (MitM) attack.

The vulnerability exists due to regression, introduced into the TLS protocol implementation that caused the TLS server to not securely construct a session ticket encryption key considering the application supplied secret. A remote attacker can bypass authentication in TLS 1.3 and recover previous conversations in TLS 1.2


Update the affected packages.

Ubuntu 20.04 LTS
libgnutls30 - 3.6.13-2ubuntu1.1
Ubuntu 19.10
libgnutls30 - 3.6.9-5ubuntu1.2

Vulnerable software versions

gnutls28 (Ubuntu package): 3.6.9, 3.6.9-1, 3.6.9-2, 3.6.9-3, 3.6.9-3ubuntu1, 3.6.9-4, 3.6.9-4build1, 3.6.9-5, 3.6.9-5ubuntu1, 3.6.9-5ubuntu1.1, 3.6.9-5ubuntu2, 3.6.9-6, 3.6.9-7, 3.6.13, 3.6.13-1, 3.6.13-2, 3.6.13-2ubuntu1, 3.6.13-2ubuntu1.1, 3.6.13-3, 3.6.13-4ubuntu1

CPE External links


Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the local network (LAN).

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability. However, proof of concept for this vulnerability is available.