CVE-2025-61911: python-ldap has sanitization bypass in ldap.filter.escape_filter_chars

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2025-10-10 · updated 2026-10-19
Weakness: CWE-75

Description

python-ldap is a lightweight directory access protocol (LDAP) client API for Python. In versions prior to 3.4.5, the sanitization method `ldap.filter.escape_filter_chars` can be tricked to skip escaping of special characters when a crafted `list` or `dict` is supplied as the `assertion_value` parameter, and the non-default `escape_mode=1` is configured. The method `ldap.filter.escape_filter_chars` supports 3 different escaping modes. `escape_mode=0` (default) and `escape_mode=2` happen to raise exceptions when a `list` or `dict` object is supplied as the `assertion_value` parameter. However, `escape_mode=1` computes without performing adequate logic to ensure a fully escaped return value. If an application relies on the vulnerable method in the `python-ldap` library to escape untrusted user input, an attacker might be able to abuse the vulnerability to launch ldap injection attacks which could potentially disclose or manipulate ldap data meant to be inaccessible to them. Version 3.4.5 fixes the issue by adding a type check at the start of the `ldap.filter.escape_filter_chars` method to raise an exception when the supplied `assertion_value` parameter is not of type `str`.

Affected products

python-ldap: before 3.4.5 — fixed in 3.4.5

How to fix

Upgrade to a fixed version: python-ldap 3.4.5. Check the vendor advisory for mitigations.

References

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