TI-2023-22912 Aliases CVE-2023-42821 GHSA-m9xq-6h2j-65r2

github.com/gomarkdown/markdown Out-of-bounds Read while parsing citations

HIGH 72CWE-125Published 2023-09-22 · Updated 2024-09-24

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: Low
Impact type: Denial of service
Confidentiality · integrity · availability: None · None · High
Fix status: Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-125 and the CVSS impact.

Summary

The package `github.com/gomarkdown/markdown` is a Go library for parsing Markdown text and rendering as HTML. Prior to pseudoversion `0.0.0-20230922105210-14b16010c2ee`, which corresponds with commit `14b16010c2ee7ff33a940a541d993bd043a88940`, parsing malformed markdown input with parser that uses parser.Mmark extension could result in out-of-bounds read vulnerability. To exploit the vulnerability, parser needs to have `parser.Mmark` extension set. The panic occurs inside the `citation.go` file on the line 69 when the parser tries to access the element past its length. This can result in a denial of service. Commit `14b16010c2ee7ff33a940a541d993bd043a88940`/pseudoversion `0.0.0-20230922105210-14b16010c2ee` contains a patch for this issue.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV

EPSS 0.01252 69th percentileScored 2026-11-07

Public exploit Yes 1 exploit referenceTagged by NVD

Fix Fixed markdown (gomarkdown): 0.0.0-20230922105210-14b16010c2eegithub.com/gomarkdown/markdown (Go): 0.0.0-20230922105210-14b16010c2ee

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: Poc
Automatable: Yes
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
gomarkdown	markdown	before 0.0.0-20230922105210-14b16010c2ee	0.0.0-20230922105210-14b16010c2ee	Patch available	CNA
—	github.com/gomarkdown/markdown (Go)	before 0.0.0-20230922105210-14b16010c2ee	0.0.0-20230922105210-14b16010c2ee	Patch available	GHSA-m9xq-6h2j-65r2

markdown Vendorgomarkdown Affected before 0.0.0-20230922105210-14b16010c2ee Fixed in 0.0.0-20230922105210-14b16010c2ee Patch available CNA
github.com/gomarkdown/markdown (Go) Vendor— Affected before 0.0.0-20230922105210-14b16010c2ee Fixed in 0.0.0-20230922105210-14b16010c2ee Patch available GHSA-m9xq-6h2j-65r2

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:gomarkdown:markdown:-:::::go::	not specified by NVD	Vulnerable	gomarkdown

cpe:2.3:a:gomarkdown:markdown:-:*:*:*:*:go:*:* Versions not specified by NVD Vulnerable ·gomarkdown

Remediation

Fix · CNA markdown (gomarkdown) Fixed in 0.0.0-20230922105210-14b16010c2ee
Fix · GHSA-m9xq-6h2j-65r2 github.com/gomarkdown/markdown (Go) Fixed in 0.0.0-20230922105210-14b16010c2ee Advisory →

Vendor assessments

Red Hat

Red Hat's page for this CVE →

Not affected: 1 product

Red Hat

Timeline

2026-10-02 Threatist record created from CVE-2023-42821
2026-10-03 Alias added: GHSA-m9xq-6h2j-65r2

References

Other 2

TI-2026-29546 github.com/gomarkdown/markdown: Out-of-bounds Read in SmartypantsRenderer CVSS 3.1HIGH 7.5

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences