Summary
python-ldap has sanitization bypass in ldap.filter.escapefilterchars
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.
Details
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 happily computes without performing adequate logic to ensure a fully escaped return value.
PoC
>>> import ldap.filter
Exploitable
>>> ldap.filter.escape_filter_chars(["abc@*()/xyz"], escape_mode=1)
'abc@*()/xyz'
>>> ldap.filter.escape_filter_chars({"abc@*()/xyz": 1}, escape_mode=1)
'abc@*()/xyz'
Not exploitable
>>> ldap.filter.escape_filter_chars("abc@*()/xyz", escape_mode=1)
'abc@\\2a\\28\\29\\2fxyz'
>>> ldap.filter.escape_filter_chars(["abc@*()/xyz"], escape_mode=0)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/usr/local/lib64/python3.12/site-packages/ldap/filter.py", line 41, in escape_filter_chars
s = assertion_value.replace('\\', r'\5c')
^^^^^^^^^^^^^^^^^^^^^^^
AttributeError: 'list' object has no attribute 'replace'
>>> ldap.filter.escape_filter_chars(["abc@*()/xyz"], escape_mode=2)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/usr/local/lib64/python3.12/site-packages/ldap/filter.py", line 36, in escape_filter_chars
r.append("\\%02x" % ord(c))
^^^^^^
TypeError: ord() expected a character, but string of length 11 found
Impact
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.
With Python being a dynamically typed language, and the commonly used JSON format supporting list and dict, it is to be expected that Python applications may commonly forward unchecked and potentially malicious list and dict objects to the vulnerable sanitization method.
The vulnerable escape_mode=1 configuration does not appear to be widely used.
An object is accessed using a type that is incompatible with its actual type, causing the runtime to interpret memory incorrectly. Typical impact: memory safety violations, unexpected behavior, or code execution.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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See it in your environmentNew to Kodem? Get a demo →Remediation advice
Add 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.
Frequently Asked Questions
- What is CVE-2025-61911? CVE-2025-61911 is a medium-severity type confusion vulnerability in python-ldap (pip), affecting versions < 3.4.5. It is fixed in 3.4.5. An object is accessed using a type that is incompatible with its actual type, causing the runtime to interpret memory incorrectly.
- Which versions of python-ldap are affected by CVE-2025-61911? python-ldap (pip) versions < 3.4.5 is affected.
- Is there a fix for CVE-2025-61911? Yes. CVE-2025-61911 is fixed in 3.4.5. Upgrade to this version or later.
- Is CVE-2025-61911 exploitable, and should I be worried? Whether CVE-2025-61911 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2025-61911 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2025-61911? Upgrade
python-ldapto 3.4.5 or later.