Vulnerability · CVE-2020-36221
An integer underflow was discovered in OpenLDAP before 2.4.57 leading to slapd crashes in the Certificate Exact Assertion processing, resulting in denial of service (s…
Published Jan 26, 2021 · catalog updated Oct 14, 2026 · the affected product
Check this week
CVE-2020-36221 is not in CISA KEV. FIRST estimates a 84.99% chance of exploitation in the next 30 days. Check whether you run the affected product.
Gaps on this record
- No plain product name is stored. The page cannot tell you which product to check.
- No vendor fix or required action is stored. Compare the linked advisory before you change production.
- Severity
- High7.5
- Known exploitation
- Not in CISA/VulnCheck KEV
- EPSS
- 84.99%
- Remediation
- Advisory link
- Affected products
- cpe apple/mac os x · cpe debian/debian linux · cpe openldap/openldap
An integer underflow was discovered in OpenLDAP before 2.4.57 leading to slapd crashes in the Certificate Exact Assertion processing, resulting in denial of service (schema_init.c serialNumberAndIssuerCheck).
Are you affected?
Enter the version you run. The result uses only the ranges stored on this record.
The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.
- cpe apple/mac os x10.14.6
- cpe debian/debian linux10.0
- cpe debian/debian linux9.0
- cpe openldap/openldapversion unspecified
How to fix CVE-2020-36221
Recommended remediation
A patch or advisory reference is linked. Open the original publisher for availability by product version.
Official advisories
What to do
Three questions, each answered from this record only. Confirm the vendor advisory before you patch.
Should you patch?
CVE-2020-36221 is not in CISA KEV. FIRST estimates a 84.99% chance of exploitation in the next 30 days. Check whether you run the affected product.
Which versions are affected?
Compare what you have installed with apple/mac os x 10.14.6; debian/debian linux 10.0; debian/debian linux 9.0. Compare the installed version with the linked vendor advisory before you change production.
What should an analyst verify?
CWE-191: Integer Underflow. EPSS 84.99%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.
Code
The project this record applies to. Exploit listings stay in References.
No public source repository is identified for this product.
Timeline
Detection, updates, and resolution for this record.
Jan 26, 2021 · NIST NVD
Detected
An integer underflow was discovered in OpenLDAP before 2.4.57 leading to slapd crashes in the Certificate Exact Assertion processing, resulting in denial of service (schema_init.c serialNumberAndIssuerCheck).
Oct 14, 2026 · NIST NVD
Updated
An integer underflow was discovered in OpenLDAP before 2.4.57 leading to slapd crashes in the Certificate Exact Assertion processing, resulting in denial of service (schema_init.c serialNumberAndIssuerCheck).
Sources
- CVE.orgVulnerability recordCVE-2020-36221
Official CVE identifier
cve.org - FIRST EPSSExploitation probabilityCVE-2020-36221
30-day exploitation probability 84.99%
first.org - NIST NVDVulnerability recordCVE-2020-36221
An integer underflow was discovered in OpenLDAP before 2.4.57 leading to slapd crashes in the Certificate Exact Assertion processing, resulting in denial of service (schema_init.c serialNumberAndIssuerCheck).
nvd.nist.gov
References
Freshness
Last verified in this catalog Oct 24, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.