How severe is CVE-2020-26307?

CVE-2020-26307 has a CVSS 4.0 base score of 8.7, rated high severity.

Is CVE-2020-26307 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (31st percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2020-26307?

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.

Does CVE-2020-26307 have an EU (EUVD) identifier?

Yes. CVE-2020-26307 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2020-18858.

When was CVE-2020-26307 published?

CVE-2020-26307 was published on 2024-10-26 and last updated on 2026-06-17.

CVE-2020-26307

CVE-2020-26307 is a high-severity vulnerability with a CVSS 4.0 base score of 8.7. 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-1333.

Key facts

Severity: High (CVSS 4.0 base score 8.7)
EPSS exploit prediction: 0% (31st percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2020-18858
Weakness: CWE-1333
Published: 2024-10-26
Last modified: 2026-06-17

Description

HTML2Markdown is a Javascript implementation for converting HTML to Markdown text. All available versions contain one or more regular expressions that are vulnerable to Regular Expression Denial of Service (ReDoS). As of time of publication, no known patches are available.

Frequently asked questions

What is CVE-2020-26307?: HTML2Markdown is a Javascript implementation for converting HTML to Markdown text. All available versions contain one or more regular expressions that are vulnerable to Regular Expression Denial of Service (ReDoS). As of time of publication, no known patches are available.
How severe is CVE-2020-26307?: CVE-2020-26307 has a CVSS 4.0 base score of 8.7, rated high severity.
Is CVE-2020-26307 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (31st percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2020-26307?: 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.
Does CVE-2020-26307 have an EU (EUVD) identifier?: Yes. CVE-2020-26307 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2020-18858.
When was CVE-2020-26307 published?: CVE-2020-26307 was published on 2024-10-26 and last updated on 2026-06-17.

References

Other CWE-1333 vulnerabilities

CVE-2026-35458 — Critical (CVSS 9.8): Gotenberg is an API for converting document formats. In 8.29.1 and earlier, Gotenberg uses dlclark/regexp2 to compile…
CVE-2023-29486 — Critical (CVSS 9.8): An issue was discovered in Heimdal Thor agent versions 3.4.2 and before 3.7.0 on Windows, allows attackers to bypass…
CVE-2026-25547 — Critical (CVSS 9.2): @isaacs/brace-expansion is a hybrid CJS/ESM TypeScript fork of brace-expansion. Prior to version 5.0.1,…
CVE-2023-29487 — Critical (CVSS 9.1): An issue was discovered in Heimdal Thor agent versions 3.4.2 and before on Windows and 2.6.9 and before on macOS,…
CVE-2026-47138 — High (CVSS 8.7): Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to…
CVE-2025-6998 — High (CVSS 8.7): ReDoS in strip_whitespaces() function in cps/string_helper.py in Calibre Web and Autocaliweb allows unauthenticated…

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