CPython: Incorrect Default Permissions
CVE-2024-4030 is a high-severity incorrect default permissions vulnerability in CPython from Python Software Foundation, with a CVSS 3.1 base score of 7.1 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions 3.8.20, 3.9.20, 3.10.15 as the first without the flaw, so updating CPython to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.3% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update CPython to 3.8.20 or 3.9.20 or 3.10.15 or 3.11.10, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Python Software Foundation | CPython | before 3.8.20; 3.9.0 up to, but not including, 3.9.20; 3.10.0 up to, but not including, 3.10.15; 3.11.0 up to, but not including, 3.11.10; 3.12.0 up to, but not including, 3.12.4; 3.13.0a1 up to, but not including, 3.13.0b1 | 3.8.20, 3.9.20, 3.10.15, 3.11.10, 3.12.4, 3.13.0b1 |
| Python | cpython | 0; 3.13.0a1 | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N. Scored by CISA (ADP).
Official description
On Windows a directory returned by tempfile.mkdtemp() would not always have permissions set to restrict reading and writing to the temporary directory by other users, instead usually inheriting the correct permissions from the default location. Alternate configurations or users without a profile directory may not have the intended permissions. If you’re not using Windows or haven’t changed the temporary directory location then you aren’t affected by this vulnerability. On other platforms the returned directory is consistently readable and writable only by the current user. This issue was caused by Python not supporting Unix permissions on Windows. The fix adds support for Unix “700” for the mkdir function on Windows which is used by mkdtemp() to ensure the newly created directory has the proper permissions.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Incorrect Default Permissions
During installation, installed file permissions are set to allow anyone to modify those files.
How developers prevent this class of flaw
- The architecture needs to access and modification attributes for files to only those users who actually require those actions.
- Compartmentalize the system to have safe areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area. Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.
More Incorrect Default Permissions vulnerabilities (CWE-276)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- github.com/python/cpython/commit/35c799d79177b962ddace2fa068101465570a29a
- github.com/python/cpython/commit/5130731c9e779b97d00a24f54cdce73ce9975dfd
- github.com/python/cpython/commit/66f8bb76a15e64a1bb7688b177ed29e26230fdee
- github.com/python/cpython/commit/6d0850c4c8188035643586ab4d8ec2468abd699e
- github.com/python/cpython/commit/81939dad77001556c527485d31a2d0f4a759033e
- github.com/python/cpython/commit/8ed546679524140d8282175411fd141fe7df070d
- github.com/python/cpython/commit/91e3669e01245185569d09e9e6e11641282971ee
- github.com/python/cpython/commit/94591dca510c796c7d40e9b4167ea56f2fdf28ca
- github.com/python/cpython/commit/c8f868dc52f98011d0f9b459b6487920bfb0ac4d
- github.com/python/cpython/commit/d86b49411753bf2c83291e3a14ae43fefded2f84
- github.com/python/cpython/commit/e1dfa978b1ad210d551385ad8073ec6154f53763
- github.com/python/cpython/commit/eb29e2f5905da93333d1ce78bc98b151e763ff46
Other references
Other vulnerabilities in CPython
- 8.2 High severity
- 9.4 Critical severity
- 7.6 High severity
- 9.2 Critical severity
- 8.4 High severity
- 7.5 High severity
Recent Incorrect Default Permissions vulnerabilities
- 7.2 High severity
- 7.5 High severity
- 7.8 High severity
- 7.8 High severity
- 9.8 Critical severity
- 8.8 High severity
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