CVE-2021-36377

Fossil before 2.14.2 and 2.15.x before 2.15.2 often skips the hostname check during TLS...

7.5 HighFix available

Fossil before 2.14.2 and 2.15.x before 2.15.2 often skips the hostname check during TLS certificate validation.

Attack profile

How easy it is to exploit

Attack vector: Network
Complexity: Low
Privileges needed: None
User interaction: None

What an attacker can affect

Confidentiality: None
Integrity: High
Availability: None

Exploit likelihood

0.57%Up 0.2 points since Jul 13, 2021

What each source reports

NVD Score used 7.5

Fossil before 2.14.2 and 2.15.x before 2.15.2 often skips the hostname check during TLS certificate validation.

Record: CVE-2021-36377
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
CVSS 2.0: 5.0 MediumAV:N/AC:L/Au:N/C:N/I:P/A:N
Weakness: CWE-295
Updated: 2026-11-02

CVE List No score

Fossil before 2.14.2 and 2.15.x before 2.15.2 often skips the hostname check during TLS certificate validation.

Record: CVE-2021-36377
Updated: 2026-11-02

EUVDEUVD-2021-22993 No score

Fossil before 2.14.2 and 2.15.x before 2.15.2 often skips the hostname check during TLS certificate validation.

Record: EUVD-2021-22993
Updated: 2026-11-03

GitHub AdvisoriesGHSA-4cqm-xv6v-78c5 No score

Fossil before 2.14.2 and 2.15.x before 2.15.2 often skips the hostname check during TLS...

Fossil before 2.14.2 and 2.15.x before 2.15.2 often skips the hostname check during TLS certificate validation.

Record: GHSA-4cqm-xv6v-78c5
Weakness: CWE-295
Updated: 2026-11-02

OSV 7.5

Fossil before 2.14.2 and 2.15.x before 2.15.2 often skips the hostname check during TLS certificate validation.

Record: CVE-2021-36377
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Updated: 2026-11-02

OSVDEBIAN-CVE-2021-36377 7.5

Fossil before 2.14.2 and 2.15.x before 2.15.2 often skips the hostname check during TLS certificate validation.

Record: DEBIAN-CVE-2021-36377
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Updated: 2026-11-02

OSVUBUNTU-CVE-2021-36377 7.5

Fossil before 2.14.2 and 2.15.x before 2.15.2 often skips the hostname check during TLS certificate validation.

Record: UBUNTU-CVE-2021-36377
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Updated: 2026-11-02

OSVMGASA-2021-0491 No score

Updated fossil packages fix security vulnerability

Client-side TLS so that it verifies that the server hostname matches its certificate (Fixed in fossil 2.14.2).

A data exfiltration bug in the server (Fixed in fossil 2.14.1).

Record: MGASA-2021-0491
Updated: 2026-11-02

Affected products

Affected packages

Affected packages
Package	Affected	Fixed
`fossil` Debian:12	before 1:2.15.2-1	1:2.15.2-1
`fossil` Debian:13	before 1:2.15.2-1	1:2.15.2-1
`fossil` Debian:14	before 1:2.15.2-1	1:2.15.2-1
`fossil` Mageia:8	before 2.14.2-1.mga8	2.14.2-1.mga8
`fossil` Ubuntu:Pro:16.04:LTS	All versions, plus listed versions 1:1.33-31:1.33-3ubuntu0.1~esm1	None known
`fossil` Ubuntu:Pro:18.04:LTS	All versions, plus listed versions 1:2.2-11:2.4-11:2.4-1build11:2.5-11:2.5-1ubuntu0.1~esm1	None known
`fossil` Ubuntu:20.04:LTS	All versions, plus listed versions 1:2.8-11:2.10-11:2.10-1ubuntu0.1	None known
`fossil` Ubuntu:22.04:LTS	All versions, plus listed versions 1:2.15.2-11:2.16-31:2.16-3build11:2.17-11:2.17-21:2.18-11:2.18-1ubuntu0.1	None known
`fossil` Ubuntu:24.04:LTS	All versions, plus listed versions 1:2.22-11:2.22-21:2.23-11:2.23-1build11:2.23-1build21:2.23-1ubuntu0.1	None known
`fossil` Ubuntu:25.10	All versions, plus listed versions 1:2.24-61:2.26-11:2.26-2	None known
`fossil` Ubuntu:26.10	All versions, plus listed versions 1:2.26-21:2.28-11:2.28-1build1	None known
`fossil` Ubuntu:26.04:LTS	All versions, plus listed versions 1:2.26-2	None known

History

History
Recorded	Changed	Sources
Nov 3, 2026	aliases	EUVD
Nov 2, 2026	first indexed	CVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2021-36377 is a high vulnerability (CVSS 7.5) in Fossil-scm Fossil, published July 12, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.57%, the 47th percentile. Fixed in fossil 1:2.15.2-1.

References

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