How severe is GHSA-r8wq-qrxc-hmcm?

GHSA-r8wq-qrxc-hmcm has a CVSS score of 6.5/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by GHSA-r8wq-qrxc-hmcm?

GHSA-r8wq-qrxc-hmcm affects the following packages: python-ldap (PyPI). Ecosystems affected: PyPI.

How do I fix GHSA-r8wq-qrxc-hmcm?

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.

How do I detect GHSA-r8wq-qrxc-hmcm in my PyPI dependencies?

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.

How do I mitigate GHSA-r8wq-qrxc-hmcm if there is no patch (or I can't update yet)?

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.

Is GHSA-r8wq-qrxc-hmcm actively exploited in the wild?

No public exploit code has been indexed for GHSA-r8wq-qrxc-hmcm yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for GHSA-r8wq-qrxc-hmcm?

GHSA-r8wq-qrxc-hmcm has an EPSS (Exploit Prediction Scoring System) score of 1.9%, placing it in the 79th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is GHSA-r8wq-qrxc-hmcm?

GHSA-r8wq-qrxc-hmcm is classified as CWE-1333 (CWE-1333). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was GHSA-r8wq-qrxc-hmcm published, and has it been updated?

GHSA-r8wq-qrxc-hmcm was published on November 29, 2021 and was last updated on July 8, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐍

🐍 PyPI

Not in CISA KEV

MEDIUM severity

ReDoS in LDAP schema parserGHSA-r8wq-qrxc-hmcm

MEDIUM

GHSA-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.

Also known asCVE-2021-46823 GHSA-qfr5-wjpw-q4c4PYSEC-2026-912

Published

Nov 29, 2021

Updated

Jul 8, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 13, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

1.9%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs79th percentile — riskier than 79% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

GHSA-r8wq-qrxc-hmcm by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 389,824 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected

🐍python-ldap

Real-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

CWE-1333

For more information

If you have any questions or comments about this advisory:

Open an issue in python-ldap tracker

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`python-ldap`	all versions	3.4.0`pip install --upgrade 'python-ldap==3.4.0'`

Affected Products

1 product · 1 configurations

Application

python-ldappython-ldap

< 3.4.0

range

Detection & mitigation playbook

Open-source dependency

Detect
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.

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 HatModerate

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…

Workaround published by Red Hat

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)

UbuntuMEDIUM

USN-5508-1Ubuntu

Frequently Asked Questions

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