CVE-2020-26409

A DOS vulnerability exists in Gitlab CE/EE >=10.3, <13.4.7,>=13.5, <13.5.5,>=13.6, <13.6.2 that...

4.3 MediumFix available

A DOS vulnerability exists in Gitlab CE/EE >=10.3, <13.4.7,>=13.5, <13.5.5,>=13.6, <13.6.2 that allows an attacker to trigger uncontrolled resource by bypassing input validation in markdown fields.

Attack profile

How easy it is to exploit

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

What an attacker can affect

Confidentiality: None
Integrity: None
Availability: Low

Exploit likelihood

1.26%Up 0.4 points since Apr 14, 2021

What each source reports

CVE List Score used 4.3

A DOS vulnerability exists in Gitlab CE/EE >=10.3, <13.4.7,>=13.5, <13.5.5,>=13.6, <13.6.2 that allows an attacker to trigger uncontrolled resource by bypassing input validation in markdown fields.

Record: CVE-2020-26409
CVSS 3.1: 4.3 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
Updated: 2026-11-02

EUVDEUVD-2020-18956 4.3

A DOS vulnerability exists in Gitlab CE/EE >=10.3, <13.4.7,>=13.5, <13.5.5,>=13.6, <13.6.2 that allows an attacker to trigger uncontrolled resource by bypassing input validation in markdown fields.

Record: EUVD-2020-18956
CVSS 3.1: 4.3 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
Updated: 2026-11-03

GitHub AdvisoriesGHSA-3jr7-57xj-6hhm No score

A DOS vulnerability exists in Gitlab CE/EE >=10.3, <13.4.7,>=13.5, <13.5.5,>=13.6, <13.6.2 that...

A DOS vulnerability exists in Gitlab CE/EE >=10.3, <13.4.7,>=13.5, <13.5.5,>=13.6, <13.6.2 that allows an attacker to trigger uncontrolled resource by bypassing input validation in markdown fields.

Record: GHSA-3jr7-57xj-6hhm
Weakness: CWE-20
Updated: 2026-11-02

NVD 4.3

A DOS vulnerability exists in Gitlab CE/EE >=10.3, <13.4.7,>=13.5, <13.5.5,>=13.6, <13.6.2 that allows an attacker to trigger uncontrolled resource by bypassing input validation in markdown fields.

Record: CVE-2020-26409
CVSS 3.1: 4.3 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
CVSS 3.1: 6.5 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CVSS 2.0: 4.0 MediumAV:N/AC:L/Au:S/C:N/I:N/A:P
Weakness: CWE-20, CWE-400
Updated: 2026-11-02

OSV 6.5

A DOS vulnerability exists in Gitlab CE/EE >=10.3, <13.4.7,>=13.5, <13.5.5,>=13.6, <13.6.2 that allows an attacker to trigger uncontrolled resource by bypassing input validation in markdown fields.

Record: CVE-2020-26409
CVSS 3.1: 6.5 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Updated: 2026-11-02

OSVUBUNTU-CVE-2020-26409 6.5

A DOS vulnerability exists in Gitlab CE/EE >=10.3, <13.4.7,>=13.5, <13.5.5,>=13.6, <13.6.2 that allows an attacker to trigger uncontrolled resource by bypassing input validation in markdown fields.

Record: UBUNTU-CVE-2020-26409
CVSS 3.1: 6.5 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CVSS 3.1: 4.3 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
Updated: 2026-11-02

OSVBIT-gitlab-2020-26409 No score

A DOS vulnerability exists in Gitlab CE/EE >=10.3, <13.4.7,>=13.5, <13.5.5,>=13.6, <13.6.2 that allows an attacker to trigger uncontrolled resource by bypassing input validation in markdown fields.

Record: BIT-gitlab-2020-26409
Updated: 2026-11-02

Affected products

Affected packages

Affected packages
Package	Affected	Fixed
`gitlab` Bitnami	before 13.6.2	13.6.2
`gitlab` Ubuntu:16.04:LTS	All versions, plus listed versions 8.4.3+dfsg-98.4.3+dfsg-128.5.8+dfsg-5	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-2020-26409 is a medium vulnerability (CVSS 4.3) in Gitlab, published December 11, 2020. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.26%, the 69th percentile. Fixed in gitlab 13.6.2.

Attack profile

How easy it is to exploit

What an attacker can affect

Exploit likelihood

What each source reports

Affected products

Affected packages

History

In short

References