CVE-2025-4138
Description
A flaw was found in the Python tarfile module. This vulnerability allows attackers to bypass extraction filters, enabling symlink targets to escape the destination directory and allowing unauthorized modification of file metadata via the use of TarFile.extract() or TarFile.extractall() with the filter= parameter set to "data" or "tar".
Statement
Versions of python36:3.6/python36 as shipped with Red Hat Enterprise Linux 8 are marked as 'Not affected' as they just provide "symlinks" to the main python3 component, which provides the actual interpreter of the Python programming language.
Mitigation
Red Hat recommends upgrading to a fixed release of Python as soon as one is available. This vulnerability can be mitigated by rejecting links inside tarfiles that use relative references to the parent directory. The upstream advisory provides this example code:
'''
# Avoid insecure segments in link names.
for member in tar.getmembers():
if not member.islnk():
continue
if os.pardir in os.path.split(member.linkname):
raise OSError("Tarfile with insecure segment ('..') in linkname")
# Now safe to extract members with the data filter.
tar.extractall(filter="data")
'''
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.5 | N/A | 7.5 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | High | N/A | High |
| Integrity Impact | None | N/A | None |
| Availability Impact | None | N/A | None |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Understanding the Weakness (CWE)
Integrity,Confidentiality,Availability
Technical Impact: Execute Unauthorized Code or Commands
The attacker may be able to create or overwrite critical files that are used to execute code, such as programs or libraries.
Integrity
Technical Impact: Modify Files or Directories
The attacker may be able to overwrite or create critical files, such as programs, libraries, or important data. If the targeted file is used for a security mechanism, then the attacker may be able to bypass that mechanism. For example, appending a new account at the end of a password file may allow an attacker to bypass authentication.
Confidentiality
Technical Impact: Read Files or Directories
The attacker may be able read the contents of unexpected files and expose sensitive data. If the targeted file is used for a security mechanism, then the attacker may be able to bypass that mechanism. For example, by reading a password file, the attacker could conduct brute force password guessing attacks in order to break into an account on the system.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
The attacker may be able to overwrite, delete, or corrupt unexpected critical files such as programs, libraries, or important data. This may prevent the product from working at all and in the case of protection mechanisms such as authentication, it has the potential to lock out product users.
Frequently Asked Questions
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