GHSA-r8wq-qrxc-hmcm — python-ldap
MEDIUMGHSA-r8wq-qrxc-hmcm is a medium-severity (CVSS 6.5) CWE-1333 vulnerability in python-ldap. A fix is available for python-ldap — see the affected versions and patch details below.
ReDoS in LDAP schema parser
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
GHSA-r8wq-qrxc-hmcm plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 379,145 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
python-ldapReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
https://github.com/python-ldap/python-ldap/issues/424
Impact
The LDAP schema parser of python-ldap 3.3.1 and earlier are vulnerable to a regular expression denial-of-service attack. The issue affects clients that use ldap.schema package to parse LDAP schema definitions from an untrusted source.
Patches
The upcoming release of python-ldap 3.4.0 will contain a workaround to prevent ReDoS attacks. The schema parser refuses schema definitions with an excessive amount of backslashes.
Workarounds
As a workaround, users can check input for excessive amount of backslashes in schemas. More than a dozen backslashes per line are atypical.
References
For more information
If you have any questions or comments about this advisory:
- Open an issue in python-ldap tracker
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | python-ldap | all versions | 3.4.0pip install --upgrade 'python-ldap==3.4.0' |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for python-ldap, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update python-ldap to 3.4.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-r8wq-qrxc-hmcm is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-r8wq-qrxc-hmcm can be triaged on real exposure rather than presence alone.
Tailored to GHSA-r8wq-qrxc-hmcm. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
Red Hat Enterprise Linux 9.0.z is affected by this vulnerability as it includes the vulnerable version of python-ldap (3.3.1). However, the issue was resolved in Red Hat Enterprise Linux 9.2 and later via RHEA-2023:2359, which rebased python-ldap to version 3.4.3 containing the upstream fix. Red Hat Enterprise Linux…
Check input for an excessive amount of backslashes in schemas. More than a dozen backslashes per line are atypical.Source: Red Hat security advisory for GHSA-r8wq-qrxc-hmcm (CC BY 4.0)
Frequently Asked Questions
Is GHSA-r8wq-qrxc-hmcm in your dependencies?
O3 Security finds GHSA-r8wq-qrxc-hmcm across PyPI dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.