Cyber Resilience

CVE-2021-28861

High

Published: 23 August 2022

Published
23 August 2022
Modified
17 December 2025
KEV Added
—
Patch
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CVSS Score v3.1 7.4 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N
EPSS Score 0.0140 80.8th percentile
Risk Priority 16 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2021-28861 is a high-severity Open Redirect (CWE-601) vulnerability in Python Python. Its CVSS base score is 7.4 (High).

Operationally, ranked in the top 19.2% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

EU & UK References

Vulnerability details

Python 3.x through 3.10 has an open redirection vulnerability in lib/http/server.py due to no protection against multiple (/) at the beginning of URI path which may leads to information disclosure. NOTE: this is disputed by a third party because the…

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http.server.html documentation page states "Warning: http.server is not recommended for production. It only implements basic security checks."

CWE(s)
CWE-601

Related Threats

No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.

Affected Assets

python
python
3.11.0 · 3.0.0 — 3.7.14 · 3.8.0 — 3.8.14 · 3.9.0 — 3.9.14
fedoraproject
fedora
35, 36, 37

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

AT-2 Literacy Training and Awareness
addresses: CWE-601

Security awareness includes verifying URLs and avoiding untrusted redirects that lead to malicious sites.

SI-10 Information Input Validation
addresses: CWE-601

Validates redirect targets and URLs to ensure they conform to allowed destinations.

References