CVE-2020-5238

What it is

The table extension in GitHub Flavored Markdown before version 0.29.0.gfm.1 takes O(n * n) time to parse certain inputs. An attacker could craft a markdown table which would take an unreasonably long time to process, causing a denial of service. This issue does not affect the upstream cmark project. The issue has been fixed in version 0.29.0.gfm.1.

At a glance

Exploitability

Can be exploited over the network with a low-privilege account. High risk of service disruption.

Exploit odds

1.6% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2020-07-01 23:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 03:21 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 1.6% in the next 30 days (EPSS).
• Severity: 6.5 MEDIUM (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2020-07-01 23:15 UTC

Last modified

2026-06-17 03:21 UTC

Exploit probability

1.6% · EPSS, next 30 days

Weakness

CWE-20 · Improper input validation

Record status

Modified

Affected

• GitHub Flavored Markdown Project GitHub Flavored Markdown < 0.29.0.gfm.1
• Fedoraproject Fedora 31
• Fedoraproject Fedora 32
• Fedoraproject Fedora 33

Attack profile CVSS 3.1 · 6.5

Attack vector

Network

Complexity

Low

Privileges needed

Low

User interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2020-5238.md and follow it. Check whether this project is affected by CVE-2020-5238. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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