Default mimetype known files writeable on Windows (CVE-2024-3220)
Published Last modified Sources: BSI, HKCERT, CVE.org, OSV, Msrc Update Guide
What is affected, what to do
There is a defect in the CPython standard library module “mimetypes” where on Windows the default list of known file locations are writable meaning other users can create invalid files to cause MemoryError to be raised on Python runtime startup or have file extensions be interpreted as the incorrect file type. This defect is caused by the default locations of Linux and macOS platforms (such as “/etc/mime.types”) also being used on Windows, where they are user-writable locations (“C:\etc\mime.types”).
Update Python Software Foundation CPython to version 3.11.18, Python Software Foundation CPython to version 3.12.16, Python Software Foundation CPython to version 3.13.18.
- Affected
- Python Software Foundation CPython
lt *..3.11.18 - Python Software Foundation CPython
lt 3.12.0..3.12.16 - Python Software Foundation CPython
lt 3.13.0..3.13.18 - Python Software Foundation CPython
lt 3.14.0..3.14.9 - Python Software Foundation CPython
lt 3.15.0..3.15.1 - Python Software Foundation CPython
lt 3.16.0a1..3.16.0
- Python Software Foundation CPython
- Fixed in
- Python Software Foundation CPython
3.11.18 - Python Software Foundation CPython
3.12.16 - Python Software Foundation CPython
3.13.18 - Python Software Foundation CPython
3.14.9 - Python Software Foundation CPython
3.15.1 - Python Software Foundation CPython
3.16.0
- Python Software Foundation CPython
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Metrics
2.3
Priority
XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.
Source: Vendor (CNA), CVSS v4
2.3
CVSS v4
Severity Low on the scale from 0 to 10.
Source: BSI, HKCERT, CVE.org, OSV, Msrc Update Guide
0.7 %
EPSS score
Low — model estimates < 1% exploitation likelihood.
Source: FIRST EPSS, percentile 53.6
Show all metrics
- Severity
- Low
Priority (0–325)
The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?
Read in glossary- 42.34 Methodology
Exploit maturity
An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.
Read in glossary- no public PoC known
XIEM Effective CVSS
XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.
Read in glossary- 2.3 Methodology
CVSS v4
CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.
Read in glossary- 2.3
EPSS score
The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.
Read in glossary- 0.7 %
- Low — model estimates < 1% exploitation likelihood.
EPSS percentile
The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.
Read in glossary- 53.6
- High — this CVE ranks above the median of all CVEs scored today (rank ≥ 36%).
KEV status
The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.
Read in glossary- —
- Published
- CISA assessment (SSVC)
- Exploitation: none known · not automatable · Technical impact: partial
- Source: CISA Vulnrichment, as of 14 February 2025
CWE
CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.
Read in glossary- CWE-426
Detection rules
No NEOSEC detection rule is available for this vulnerability yet.
Classification under NIS2 and CRA
Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.
NIS2
NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.
Read in glossary- Handle the vulnerability in regular vulnerability handling under Art. 21(2)(e) NIS2.
CRA
The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.
Read in glossary- From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
ISO/IEC 27001
ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.
Read in glossary- Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.
Description
There is a defect in the CPython standard library module “mimetypes” where on Windows the default list of known file locations are writable meaning other users can create invalid files to cause MemoryError to be raised on Python runtime startup or have file extensions be interpreted as the incorrect file type. This defect is caused by the default locations of Linux and macOS platforms (such as “/etc/mime.types”) also being used on Windows, where they are user-writable locations (“C:\etc\mime.types”). To work-around this issue a user can call mimetypes.init() with an empty list (“[]”) on Windows platforms to avoid using the default list of known file locations.
Source: BSI CSAF, BSI WID Portal, HKCERT (CC BY 3.0 HK) · HKCERT rating: medium, cvelistv5, NVD (NIST), OSV (Open Source Vulnerabilities), Microsoft Security Update Guide
Affected products
The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.
| Affected versions | Fixed in | ||
|---|---|---|---|
| Python Software Foundation | CPython |
|
|
| IBM | SPSS |
|
|
| NetApp | ActiveIQ Unified Manager |
|
|
| Open Source | Python |
|
|
Distribution and container packages (1)
Downstream packages (e.g. Bitnami, Debian, Ubuntu, Red Hat). Versions refer to the distribution, not the vendor.
| Affected versions | Fixed in | ||
|---|---|---|---|
| bitnami | python-min |
|
|
Vendors and products
Weakness classes (CWE)
CWE-426Untrusted Search Path
Base
The product searches for critical resources using an externally-supplied search path that can point to resources that are not under the product's direct control.
Entry at MITRE CWE-426
References & sources
- mail.python.orgarchives/list/security-announce@python.org/thread/CDXW34ND2LSAO…advisory, Vendor advisory
- openwall.comlists/oss-security/2025/02/14/8
- security.netapp.comadvisory/ntap-20250314-0001
- github.compython/cpython/issues/159428report, Issue tracking
- github.compython/cpython/commit/04a29bf8f9ff8526cd96cb7368400173303a390aPatch, fix
- github.compython/cpython/commit/5550519259656cbb8eeac09e3dbc0d5c248a4deafix, Patch
- github.compython/cpython/commit/76f4555c4ff10f5dda58d6528c17787df41e256cfix, Patch
- github.compython/cpython/commit/2f00690fd5a75305e02c99628a41439179266f29fix, Patch
- github.compython/cpython/commit/35dd324f6e30735162a68cde84bb04a169004325fix, Patch
- github.compython/cpython/commit/8d4286a3f41d36f42c4b4cf5c4451a5a8c23fe87fix, Patch
Changes to this CVE
Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).
Record modifiedpython.org
Show 4 original changes
Individual changes of this event as published by NVD Type Action Before After Affected versions (publisher) added —Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2024/3xxx/CVE-2024-3220.json">CVE-2024-3220</a>Reference added —https://github.com/python/cpython/commit/2f00690fd5a75305e02c99628a41439179266f29Reference added —https://github.com/python/cpython/commit/35dd324f6e30735162a68cde84bb04a169004325Reference added —https://github.com/python/cpython/commit/8d4286a3f41d36f42c4b4cf5c4451a5a8c23fe87Source identifier: cna@python.org
Record modifiedpython.org
1 individual change: Affected versions (publisher)
Show the original change
Individual changes of this event as published by NVD Type Action Before After Affected versions (publisher) added —Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2024/3xxx/CVE-2024-3220.json">CVE-2024-3220</a>Source identifier: cna@python.org
Record modifiedpython.org
Show 2 original changes
Individual changes of this event as published by NVD Type Action Before After Reference added —https://github.com/python/cpython/commit/5550519259656cbb8eeac09e3dbc0d5c248a4deaReference added —https://github.com/python/cpython/commit/76f4555c4ff10f5dda58d6528c17787df41e256cSource identifier: cna@python.org
Record modifiedpython.org
Show the original change
Individual changes of this event as published by NVD Type Action Before After Reference added —https://github.com/python/cpython/commit/04a29bf8f9ff8526cd96cb7368400173303a390aSource identifier: cna@python.org
Record modifiedpython.org
Show 4 original changes
Individual changes of this event as published by NVD Type Action Before After Affected versions (publisher) added —Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2024/3xxx/CVE-2024-3220.json">CVE-2024-3220</a>Reference added —https://github.com/python/cpython/issues/159428Reference added —https://mail.python.org/archives/list/security-announce@python.org/thread/CDXW34ND2LSAOYAR5N6UNONP4ZBX4D6R/Reference removed https://mail.python.org/archives/list/security-announce@python.org/thread/CDXW34ND2LSAOYAR5N6UNONP4ZBX4D6R/—Source identifier: cna@python.org
Show one older change
Record modifiedCVE Program
Show 4 original changes
Individual changes of this event as published by NVD Type Action Before After Reference added —http://www.openwall.com/lists/oss-security/2025/02/14/8Reference added —https://security.netapp.com/advisory/ntap-20250314-0001/Reference removed http://www.openwall.com/lists/oss-security/2025/02/14/8—Reference removed https://security.netapp.com/advisory/ntap-20250314-0001/—Source identifier: af854a3a-2127-422b-91ae-364da2661108
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<a href="https://intel.neosec.eu/en/cve/CVE-2024-3220"><img src="https://intel.neosec.eu/badge/cve/CVE-2024-3220.svg?lang=en" alt="CVE-2024-3220 – NEOSEC Intel" height="20"></a>