PythonApplication
CVE-2019-13404
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedThe MSI installer for Python through 2.7.16 on Windows defaults to the C:\Python27 directory, which makes it easier for local users to deploy Trojan horse code. (This also affects old 3.x releases before 3.5.) NOTE: the vendor's position is that it is the user's responsibility to ensure C:\Python27 access control or choose a different directory, because backwards compatibility requires that C:\Python27 remain the default for 2.7.x
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceThe MSI installer for Python versions through 2.7.16 on Windows defaults to installing in the C:\Python27 directory, creating a predictable location that local users may be able to write to, enabling deployment of Trojan horse code. This also affects older Python 3.x releases before 3.5. The vulnerability stems from the predictable default path being potentially world-writable or accessible to unprivileged local users.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
PythonApplication
<= 2.7.16>= 3.0.0, < 3.5.0CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Local
- Complexity
- Low
- Privileges
- None
- User interaction
- Required
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Locate Python installation directoryCheck if Python is installed at the default predictable path C:\Python27 (for Python 2.x) by examining the filesystem. For Python 3.x < 3.5, also check common default installation paths like C:\Python35, C:\Python34, C:\Python33, C:\Python32, C:\Python31, C:\Python30.Affected if Python is installed at C:\Python27 or similar default paths (C:\Python3x) that are potentially world-writable.
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Determine installed Python versionRun 'python --version' or check the python.exe version properties in the installation directory to identify the exact version number.Affected if The installed version is Python 2.7.16 or earlier, OR Python 3.0.0 through any version before 3.5.0.
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Verify NTFS permissions on installation directoryRight-click the Python installation folder, go to Properties > Security tab, and examine the permissions. Use 'icacls C:\Python27' or equivalent command to list all granted permissions to users and groups.Affected if The directory grants write or execute permissions to Users, Everyone, or other unprivileged accounts, or has weak ACLs that allow local non-admin users to modify contents.
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Confirm executable integrityCompare the hash (SHA256 or MD5) of python.exe and other critical executables in the installation directory against known-good values from a trusted source, or verify digital signatures if available.Affected if Executables have been modified, show unexpected hashes, or lack valid signatures, indicating potential Trojan horse injection.
You are affected if Python is installed at the default predictable path (C:\Python27 for 2.x, similar for older 3.x) AND the version falls within <=2.7.16 or >=3.0.0/<3.5.0 AND the directory permissions allow unprivileged local users to write or modify files.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor data3.5.0
Install Python to a non-default directory with proper access controls, or ensure the default C:\Python27 directory has restrictive NTFS permissions to prevent unauthorized code execution by local users.
Fix this in Python
Scoped from the published advisory
- Consultation2.0 h
- Implementation2.0 h
- Testing1.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,744.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2019-13404 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2019-13404 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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