@digitalocean/do-markdownit has Type Confusion vulnerability

published 2025-09-19 13 mo ago modified 2026-06-17 4 mo ago also GHSA-2h8j-8r9p-849f , EUVD-2025-30235

cvss: 5.4; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.4%; EPSS 0.4% chance of exploitation in 30 days, percentile 33%
public exploits: 0; none known

In the @digitalocean/do-markdownit package through 1.16.1 (in npm), the callout and fence_environment plugins perform .includes substring matching if allowedClasses or allowedEnvironments is a string (instead of an array).

CISA SSVC

Exploitation: Proof of concept is public
Automatable: no
Technical impact: partial
Assessed: 13 mo ago (2025-09-19)

Exploit prediction

0.39% chance of exploitation in the next 30 days, higher than 33% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

gist.github.com https://gist.github.com/thesmartshadow/dd19665f1f51a4e3c7a766e70c9eafd0 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	3.1	5.4	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N
NVD	3.1	9.8	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
GitHub	3.1	5.4	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N

Affected packages

ecosystem	package	affected	fixed in
npm	@digitalocean/do-markdownit	<=1.16.1	no fix listed

Affected products

DigitalOcean @digitalocean/do-markdownit

Classification

Weakness

CWE-843 Access of Resource Using Incompatible Type

References

gist.github.com /thesmartshadow/dd19665f1f51a4e3c7a766e70c9eafd0
exploit, web, third-party-advisory
github.com /digitalocean/do-markdownit
package, product
npmjs.com /package/@digitalocean/do-markdownit
web, product
nvd.nist.gov /vuln/detail/CVE-2025-59717
advisory

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary