Public proof of concept

CVE-2020-13777

A public proof of concept exists; no exploitation attested.

Published2020-06-04
WeaknessCWE-327

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC

2020-06-0407:15CVE publishedNVD
2026-10-2319:23First public proof of conceptPoC-in-GitHub
2026-10-2319:23EPSS crossed 10 %FIRST EPSS

Observed activity

isMalicious corpus · updated 2026-10-23 18:48 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2020-13777?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2020-13777?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

Canonical ubuntu linux

Branch	Affected	Fixed in	Source
19.10	= 19.10	no fix published	NVD
20.4	= 20.04	no fix published	NVD

Fedoraproject fedora

Branch	Affected	Fixed in	Source
31.x	= 31	no fix published	NVD
32.x	= 32	no fix published	NVD

Debian debian linux

Branch	Affected	Fixed in	Source
10.0	= 10.0	no fix published	NVD

1 more product in the sources.

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

Advisories and patches

gnutls.orgVendor Advisory

Detection

read 2026-10-23 19:23 UTC

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: 3 repositories, unverified0xxon/cve-2020-13777shigeki/challenge_CVE-2020-13777prprhyt/PoC_TLS1_3_CVE-2020-13777

Sources

NVDCVSS 3.17.4read 2026-10-23
NVDCVSS 2.05.8read 2026-10-23
NVDweakness (CWE)CWE-327read 2026-10-23
FIRST EPSSEPSS score22.3 %read 2026-10-23
PoC-in-GitHubproof of concept3read 2026-10-23

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Published: 2020-06-04
Last Modified: 2026-10-14
NVD status: Modified

Frequently asked questions

What is CVE-2020-13777?

Is CVE-2020-13777 actively exploited?

Active exploitation of CVE-2020-13777 has not been confirmed. Its EPSS score was 22.3% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2020-13777?

CVE-2020-13777 has a CVSS v3 base score of 7.4 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N.

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