Ubuntu update for GnuTLS



Risk Medium
Patch available YES
Number of vulnerabilities 1
CVE-ID CVE-2020-13777
CWE-ID CWE-300
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 Bulletin

This security bulletin contains one medium risk vulnerability.

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

EUVDB-ID: #VU28557

Risk: Medium

CVSSv4.0: 2.1 [CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:P/U:Green]

CVE-ID: CVE-2020-13777

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

Exploit availability: Yes

Description

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

Mitigation

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 - 3.6.13-4ubuntu1

CPE2.3 External links

https://usn.ubuntu.com/4384-1/


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.



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