CVE-2023-42821
CVE-2023-42821 is a high-severity vulnerability in Gomarkdown Markdown with a CVSS 3.x base score of 7.5. 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-125.
Key facts
- Severity: High (CVSS 3.x base score 7.5)
- EPSS exploit prediction: 1% (60th percentile)
- Actively exploited: Not listed in CISA KEV
- Weakness: CWE-125
- Affected product: Gomarkdown Markdown
- Published:
- Last modified:
Description
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.
Frequently asked questions
- What is CVE-2023-42821?
- 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.
- How severe is CVE-2023-42821?
- CVE-2023-42821 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
- Is CVE-2023-42821 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (60th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2023-42821?
- CVE-2023-42821 affects Gomarkdown Markdown. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2023-42821?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
- When was CVE-2023-42821 published?
- CVE-2023-42821 was published on 2023-09-22 and last updated on 2026-06-17.
References
- https://github.com/gomarkdown/markdown/blob/7478c230c7cd3e7328803d89abe591d0b61c41e4/parser/citation.go#L69
- https://github.com/gomarkdown/markdown/commit/14b16010c2ee7ff33a940a541d993bd043a88940
- https://github.com/gomarkdown/markdown/security/advisories/GHSA-m9xq-6h2j-65r2
Affected products (1)
- cpe:2.3:a:gomarkdown:markdown:-:*:*:*:*:go:*:*
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