Pyramid static view path traversal up one directory

CVE-2023-40587 → View on GitHub ↗ View on CVE.org ↗ View on NVD ↗

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:

  • https://github.com/python/cpython/issues/106242
  • https://github.com/python/cpython/pull/106816

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

  • https://owasp.org/www-community/attacks/Path_Traversal
  • VN: JVN#41113329
  • TN: JPCERT#93311166

Thanks

  • Masashi Yamane of LAC Co., Ltd

Basic information

Type
reviewed
Severity
medium
Advisory on GitHub
Open advisory ↗
Repository advisory
Open repository advisory ↗
Source code
Browse source ↗
Published (advisory)
2023-08-25 18:49:25 UTC
Updated
2024-02-16 22:38:40 UTC
GitHub reviewed
2023-08-25 18:49:25 UTC
NVD published
2023-08-25

EPSS Score

Score Percentile
0.33% 55.53%

CVSS Scores

Base score Version Severity Vector
5.3 3.1 —
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.

Identifiers

Type Value
GHSA GHSA-j8g2-6fc7-q8f8 ↗
CVE CVE-2023-40587 ↗

CWEs

CWE id Name
CWE-22 Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

Affected packages (1)

Vulnerable version ranges and first patched releases as published by GitHub.

Ecosystem Package Vulnerable range First patched Vulnerable functions
pip pyramid >= 2.0.0, < 2.0.2 2.0.2 —

References

cvelogic Threat Intelligence