CVE-2021-30027

MEDIUMNVD 5.55.5—

5.5

md_analyze_line in md4c.c in md4c 0.4.7 allows attackers to trigger use of uninitialized memory, and cause a denial of service via a malformed Markdown document.

CVSS v3: 5.5
EG Score: 5.5(medium)
EPSS: 50.3%
KEV: Not listed

Published

April 29, 2021

Last Modified

November 21, 2024

References (4)

cve@mitrehttps://github.com/mity/md4c/commit/4fc808d8fe8d8904f8525bb4231d854f45e23a19
cve@mitrehttps://github.com/mity/md4c/issues/155
af854a3a-2127-422b-91ae-364da2661108https://github.com/mity/md4c/commit/4fc808d8fe8d8904f8525bb4231d854f45e23a19
af854a3a-2127-422b-91ae-364da2661108https://github.com/mity/md4c/issues/155

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

CWE-908Use of Uninitialized Resource

Data Freshness Timeline

(refreshed 11× in last 7d / 18× in last 30d)

Every time one of our enrichment pipelines (NVD, MITRE cvelistV5, EPSS, CISA KEV, GHSA, OSV, vendor advisories) ran against this CVE. Most recent first.

2026-06-02 20:11 UTCepss_batch
2026-06-02 20:11 UTCepss_batch
2026-06-02 20:11 UTCepss_batch
2026-06-01 13:50 UTCepss_batch
2026-06-01 13:50 UTCepss_batch
2026-05-31 22:29 UTCepss_batch
2026-05-31 22:29 UTCepss_batch
2026-05-31 00:15 UTCepss_batch
2026-05-29 13:42 UTCepss_batch
2026-05-28 13:43 UTCepss_batch
2026-05-28 13:43 UTCepss_batch
2026-05-27 13:39 UTCepss_batch
2026-05-27 13:39 UTCepss_batch
2026-05-26 13:42 UTCepss_batch
2026-05-26 07:17 UTCepss_batch
2026-05-26 07:17 UTCepss_batch
2026-05-23 08:08 UTCEG score recompute
2026-05-23 08:08 UTCGHSA enrichment

Frequently asked(5)

What is CVE-2021-30027?

CVE-2021-30027 is a medium vulnerability published on April 29, 2021. mdanalyzeline in md4c.c in md4c 0.4.7 allows attackers to trigger use of uninitialized memory, and cause a denial of service via a malformed Markdown document.

When was CVE-2021-30027 disclosed?

CVE-2021-30027 was first published in the National Vulnerability Database on April 29, 2021, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.

Is CVE-2021-30027 actively exploited?

CVE-2021-30027 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 50.3% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.

What is the CVSS score of CVE-2021-30027?

CVE-2021-30027 has a CVSS v3 base score of 5.5 (NVD).

How do I remediate CVE-2021-30027?

Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-30027, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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CVE-2021-30027

📅 Published

🔄 Last Modified

🔗 References (4)

Weakness Classification(1)

Data Freshness Timeline

❓ Frequently asked(5)

Dependency Blast Radius

Is Your Infrastructure Affected by CVE-2021-30027?

🔗 Related CVEs(same CWE)

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Published

Last Modified

References (4)

Frequently asked(5)

Related CVEs(same CWE)