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Pyramid static view path traversal up one directory

Low
digitalresistor published GHSA-j8g2-6fc7-q8f8 Aug 25, 2023

Package

pip pyramid (pip)

Affected versions

<=2.0.1,>=2.0.0

Patched versions

2.0.2

Description

Impact

This impacts users of Python 3.11 that are using a Pyramid static view with a full filesystem path and have a index.html file that is located exactly one directory above the location of the static view's file system path. No further path traversal exists, and the only file that could be disclosed accidentally is index.html.

Example:

config.add_static_view(name='static', path='/usr/src/app/static', cache_max_age=0)

And directory tree:

/usr/src/app \
              | - static \
                          | - file.css
                          | - index.html
                          | - ...
              | - index.html <-- (this file could be disclosed with this bug)

Patches

Pyramid now will reject any path that contains a null-byte out of caution. While valid in directory/file names, we would strongly consider it a mistake to use null-bytes in naming files/directories.

Secondly, Python 3.11, and 3.12 has fixed the underlying issue in os.path.normpath to no longer truncate on the first 0x00 found, returning the behavior to pre-3.11 Python, un an as of yet unreleased version, see:

At the time the following Python versions are not fixed:

  • Python 3.11.0 to 3.11.4
  • Python 3.12.0a1 to 3.12.0rc1

Fixes will be available in: Python 3.12.0rc2 or 3.11.5.

Please note that release candidates of Python are not production ready and should not be used for production workloads.

Workarounds

Use a version of Python 3 that is not affected. Downgrade to Python 3.10 series temporarily, or wait till Python 3.11.5 is released and upgrade to the latest version of Python 3.11 series.

References

Thanks

  • Masashi Yamane of LAC Co., Ltd

Severity

Low

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
Required
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:N

CVE ID

CVE-2023-40587