sniff_csv provides filesystem access even when enable_external_access is disabled in duckdb

### Summary Content in filesystem is accessible for reading using `sniff_csv`, even with `enable_external_access=false`. ### Details During a pentest, a security researcher was able to access environment variable data and other system data by using the `sniff_csv` function, even though we set `enable_external_access` to false. ### PoC ```SQL SET enable_external_access=false; SET lock_configuration=true; SELECT Columns FROM sniff_csv('/proc/self/environ'); ``` ### Impact Provides an attacker with access to filesystem even when access is expected to be disabled and other similar functions do NOT provide access. For example `select * from read_csv('/proc/self/environ')` fails with a permission error. There seems to be two vectors to this vulnerability: 1. Access to files that should otherwise not be allowed. (We expect `Permission Error: Scanning CSV files is disabled through configuration` and not to provide any access to the file or even acknowledge that it exists). 2. The content from a (non-csv?) file can be read (e.g. `/etc/hosts`, `proc/self/environ`, etc) even though that doesn't seem to be the intent of the sniff_csv function (my understanding is it's intending to provide information about the shape of the data, but not provide the data itself). ### Workaround It is possible to work around the issue by disabling the local file system using the `disabled_filesystems` setting: ```SQL SET disabled_filesystems='LocalFileSystem'; SET lock_configuration=true; SELECT Columns FROM sniff_csv('/proc/self/environ'); ``` will result in `Permission Error: File system LocalFileSystem has been disabled by configuration`. ### Fix A fix has been merged into the `main` branch (https://github.com/duckdb/duckdb/pull/13133), and will be released with the next DuckDB release.

CVSS 3.1

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Severity from

GitHub (reviewed advisory)

Weakness

CWE-200

Also known as

CVE-2024-41672, PYSEC-2024-203

• github.com/duckdb/duckdb/security/advisories/GHSA-w2gf-jxc9-pf2q
• nvd.nist.gov/vuln/detail/CVE-2024-41672
• github.com/duckdb/duckdb/pull/13133
• github.com/duckdb/duckdb/commit/c9b7c98aa0e1cd7363fe8bb8543a95f38e980d8a
• github.com/duckdb/duckdb
• github.com/pypa/advisory-database/tree/main/vulns/duckdb/PYSEC-2024-203.yaml