markdown-it up to 14.1.x Markdown Parser replaceAt resource consumption

Summaryinfo

A vulnerability has been found in markdown-it up to 14.1.x and classified as problematic. The impacted element is the function replaceAt of the component Markdown Parser. The manipulation leads to resource consumption. This vulnerability is uniquely identified as CVE-2026-48988. The attack is possible to be carried out remotely. No exploit exists. The affected component should be upgraded.

Detailsinfo

A vulnerability was found in markdown-it up to 14.1.x and classified as problematic. This issue affects the function replaceAt of the component Markdown Parser. The manipulation with an unknown input leads to a resource consumption vulnerability. Using CWE to declare the problem leads to CWE-400. The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources. Impacted is availability. The summary by CVE is:

markdown-it is a Markdown parser. Versions 14.1.1 and below contain a denial-of-service vulnerability when typographer: true is enabled, due to quadratic (O(n^2)) processing in the smartquotes rule. The issue stems from repeatedly modifying strings with replaceAt(), which performs O(n) slicing and concatenation per quote character. This can cause excessive CPU consumption when parsing quote-heavy, user-supplied markdown and may let attackers degrade or disrupt service availability. Although typographer is disabled by default, many production apps enable it for smart typography, making the issue relevant. This issue has been fixed in version 14.2.0.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-48988 since 05/27/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1499 for this issue.

Upgrading to version 14.2.0 eliminates this vulnerability. Applying the patch 9ce2087562c45d1e5ddd9f76b990f4b3fbe040e5 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-37799). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Name

• markdown-it

Version

• 14.0
• 14.1

License

• open-source

Website

• Product: https://github.com/markdown-it/markdown-it/

CPE 2.3info

• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Discussion