The mkdocs 1.2.2 built-in dev-server allows directory traversal using the port 8000…
Priority HIGH 66CWE-22Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Information disclosure
- Confidentiality · integrity · availability
- High · None · None
- Fix status
- Fixed
Attack profile from CVSS 3.1 · NVD. Fix status from CNA and GitHub. Impact type from CWE-22 and the CVSS impact.
Summary
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
Why it matters now
Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.14984 96th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed mkdocs (PyPI): 1.2.3
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | — | all versions | — | No fix listed | CNA |
| — | mkdocs (PyPI) | 1.2.2 to before 1.2.3 | 1.2.3 | Patch available | GHSA-qh9q-34h6-hcv9 |
- — Vendor— Affected all versions Fixed in — No fix listed CNA
- mkdocs (PyPI) Vendor— Affected 1.2.2 to before 1.2.3 Fixed in 1.2.3 Patch available GHSA-qh9q-34h6-hcv9
Remediation
- Fix · GHSA-qh9q-34h6-hcv9 mkdocs (PyPI) Fixed in 1.2.3 Advisory →
Vendor assessments
Timeline
- 2026-10-02 Threatist record created from CVE-2021-40978
- 2026-10-03 Alias added: GHSA-qh9q-34h6-hcv9
References
Advisory 4
Other 5
- https://github.com/mkdocs/mkdocs/pull/2604
- https://github.com/mkdocs/mkdocs/commit/1b15412f4caae476c262210315fd068d0521a833
- https://github.com/mkdocs/mkdocs/commit/57540911a0d632674dd23edec765189f96f84f6b
- https://github.com/mkdocs/mkdocs/releases/tag/1.2.3
- https://github.com/pypa/advisory-database/tree/main/vulns/mkdocs/PYSEC-2021-878.yaml
Sources
- CVE-2021-40978 · CVE Program
- CVE-2021-40978 · NVD
- FIRST EPSS
- GHSA-qh9q-34h6-hcv9 · GitHub Advisory Database · CC BY 4.0
- CVE-2021-40978 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences