How severe is CVE-2021-30027?

CVE-2021-30027 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-30027 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (49th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-30027?

CVE-2021-30027 affects Md4c Project Md4c. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-30027?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-30027 published?

CVE-2021-30027 was published on 2021-04-29 and last updated on 2026-06-17.

CVE-2021-30027

CVE-2021-30027 is a medium-severity vulnerability in Md4c Project Md4c with a CVSS 3.x base score of 5.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-908.

Key facts

Severity: Medium (CVSS 3.x base score 5.5)
CVSS v2: 4.3
EPSS exploit prediction: 1% (49th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-908
Affected product: Md4c Project Md4c
Published: 2021-04-29
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-2021-30027?: 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.
How severe is CVE-2021-30027?: CVE-2021-30027 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-30027 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (49th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-30027?: CVE-2021-30027 affects Md4c Project Md4c. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-30027?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-30027 published?: CVE-2021-30027 was published on 2021-04-29 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:md4c_project:md4c:0.4.7:*:*:*:*:*:*:*

More vulnerabilities in Md4c Project Md4c

CVE-2018-11547 — Critical (CVSS 9.8): md_is_link_reference_definition_helper in md4c 0.2.5 has a heap-based buffer over-read because md_is_link_label…
CVE-2018-11546 — Critical (CVSS 9.8): md4c 0.2.5 has a heap-based buffer over-read because md_is_named_entity_contents has an off-by-one error.
CVE-2018-11545 — Critical (CVSS 9.8): md4c 0.2.5 has a heap-based buffer overflow in md_merge_lines because md_is_link_label mishandles the case of a link…
CVE-2018-11536 — Critical (CVSS 9.8): md4c before 0.2.5 has a heap-based buffer overflow because md_split_simple_pairing_mark mishandles splits.
CVE-2018-12112 — High (CVSS 7.8): md_build_attribute in md4c.c in md4c 0.2.6 allows remote attackers to cause a denial of service (Segmentation fault and…
CVE-2020-26148 — High (CVSS 7.5): md_push_block_bytes in md4c.c in md4c 0.4.5 allows attackers to trigger use of uninitialized memory, and cause a denial…

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Other CWE-908 (Use of Uninitialized Resource) vulnerabilities

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CVE-2024-32611 — Critical (CVSS 9.8): HDF5 Library through 1.14.3 may use an uninitialized value in H5A__attr_release_table in H5Aint.c.
CVE-2023-24941 — Critical (CVSS 9.8): Windows Network File System Remote Code Execution Vulnerability
CVE-2022-26437 — Critical (CVSS 9.8): In httpclient, there is a possible out of bounds write due to uninitialized data. This could lead to remote escalation…
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Browse all CWE-908 (Use of Uninitialized Resource) vulnerabilities →