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Vulnerability record · CVE-2021-40978 · published 7 October 2021

CVE-2021-40978: Mkdocs path traversal vulnerability

Mkdocs · Mkdocs

The mkdocs 1.2.2 built-in dev-server allows directory traversal using the port 8000, enabling remote exploitation to obtain :sensitive information. NOTE: the vendor has disputed this as described in https://github.com/mkdocs/mkdocs/issues/2601.] and https://github.com/nisdn/CVE-2021-40978/issues/1

7.5 CVSS 3.1 High EPSS 15% · top 3.4% CWE-22 · Path traversal
7.5CVSS 3.1 base score, v2 5.0
15%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
8References, 2 tagged exploit
17 Jun 2026Last modified by NVD

Description

The mkdocs 1.2.2 built-in dev-server allows directory traversal using the port 8000, enabling remote exploitation to obtain :sensitive information. NOTE: the vendor has disputed this as described in https://github.com/mkdocs/mkdocs/issues/2601.] and https://github.com/nisdn/CVE-2021-40978/issues/1

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/mkdocs/mkdocs Third Party Advisory
https://github.com/mkdocs/mkdocs/issues/2601 Issue TrackingThird Party Advisory
https://github.com/nisdn/CVE-2021-40978 ExploitThird Party Advisory
https://github.com/nisdn/CVE-2021-40978/issues/1 Issue TrackingThird Party Advisory
https://github.com/mkdocs/mkdocs Third Party Advisory
https://github.com/mkdocs/mkdocs/issues/2601 Issue TrackingThird Party Advisory
https://github.com/nisdn/CVE-2021-40978 ExploitThird Party Advisory
https://github.com/nisdn/CVE-2021-40978/issues/1 Issue TrackingThird Party Advisory

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2021-40978), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.