How severe is CVE-2021-46823?

CVE-2021-46823 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 CVE-2021-46823?

CVE-2021-46823 affects the following packages: python-ldap (PyPI). Ecosystems affected: PyPI.

How do I fix CVE-2021-46823?

Update python-ldap to 3.4.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-46823 is resolved across your whole dependency graph.

How do I detect CVE-2021-46823 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 CVE-2021-46823 if there is no patch (or I can't update yet)?

Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Is CVE-2021-46823 actively exploited in the wild?

No public exploit code has been indexed for CVE-2021-46823 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 CVE-2021-46823?

CVE-2021-46823 has an EPSS (Exploit Prediction Scoring System) score of 2.0%, placing it in the 81th 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 CVE-2021-46823?

CVE-2021-46823 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 CVE-2021-46823 published, and has it been updated?

CVE-2021-46823 was published on June 18, 2022 and was last updated on October 20, 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

CVE-2021-46823 — python-ldap

MEDIUM

CVE-2021-46823 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.

Denial of Service in python-ldap

Also known asGHSA-qfr5-wjpw-q4c4 GHSA-r8wq-qrxc-hmcmPYSEC-2026-912

Published

Jun 18, 2022

Updated

Oct 20, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

2.0%probability of exploitation in next 30 days

Lower Risk+0.03%

Lower risk than most CVEs81th percentile — riskier than 81% of all scored CVEsHighest risk

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

How urgent is this, really

Where this sits among everything scored

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

python-ldap before 3.4.0 is vulnerable to a denial of service when ldap.schema is used for untrusted schema definitions, because of a regular expression denial of service (ReDoS) flaw in the LDAP schema parser. By sending crafted regex input, a remote authenticated attacker could exploit this vulnerability to cause a denial of service condition.

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 CVE-2021-46823 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

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