CVE-2021-40978

HIGH NUCLEI

mkdocs 1.2.2 - Path Traversal via Dev-Server Port 8000

Title source: llm
STIX 2.1

Exploitation Summary

EIP tracks 1 public exploit for CVE-2021-40978. PoCs published by nisdn. A Nuclei detection template is also available.

AI-analyzed exploit summary This repository provides a proof-of-concept for CVE-2021-40978, demonstrating a directory traversal vulnerability in Mkdocs 1.2.2's built-in dev-server. The exploit allows unauthorized access to arbitrary files outside the root directory via crafted HTTP requests.

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

Exploits (1)

nomisec WORKING POC 2 stars
by nisdn · poc
https://github.com/nisdn/CVE-2021-40978

This repository provides a proof-of-concept for CVE-2021-40978, demonstrating a directory traversal vulnerability in Mkdocs 1.2.2's built-in dev-server. The exploit allows unauthorized access to arbitrary files outside the root directory via crafted HTTP requests.

Classification
Working Poc 90%
Attack Type
Info Leak
Complexity
Trivial
Reliability
Reliable
Target: Mkdocs 1.2.2
No auth needed
Prerequisites: Mkdocs 1.2.2 with dev-server running on port 8000
devstral-2 · analyzed Feb 16, 2026 Full analysis →

Nuclei Templates (1)

MKdocs 1.2.2 - Directory Traversal
HIGHby pikpikcu

References (4)

Core 4
Core References
Third Party Advisory x_refsource_misc
https://github.com/mkdocs/mkdocs
Exploit, Third Party Advisory x_refsource_misc
https://github.com/nisdn/CVE-2021-40978
Issue Tracking, Third Party Advisory x_refsource_misc
https://github.com/mkdocs/mkdocs/issues/2601
Issue Tracking, Third Party Advisory x_refsource_misc
https://github.com/nisdn/CVE-2021-40978/issues/1

Scores

CVSS v3 7.5
EPSS 0.7972
EPSS Percentile 99.1%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

CISA SSVC

Vulnrichment
Exploitation poc
Automatable no
Technical Impact partial

Details

CWE
CWE-22
Status published
Products (2)
mkdocs/mkdocs 1.2.2
pypi/mkdocs 1.2.2 - 1.2.3PyPI
Published Oct 07, 2021
Tracked Since Feb 18, 2026