CVE-2020-36228Public exploitNetwork attack vector

Remote service crash via certificate assertion underflow

Published Jan 25, 2021 · Updated Aug 4, 2024

Integer underflow in OpenLDAP slapd before 2.4.57 allows remote attackers to crash the directory server via a crafted LDAP search. A malformed Certificate List Exact Assertion drives issuerAndThisUpdateCheck in schema_init.c to index past the issuer buffer after its length underflows. No authentication or user interaction is required; processing the crafted search request terminates slapd and interrupts directory service.

CVSS severity7.5
High
EPSS probability84.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Integer underflow in OpenLDAP slapd before 2.4.57 allows remote attackers to crash the directory server via a crafted LDAP search. A malformed Certificate List Exact Assertion drives issuerAndThisUpdateCheck in schema_init.c to index past the issuer buffer after its length underflows. No authentication or user interaction is required; processing the crafted search request terminates slapd and interrupts directory service.

The record

CVE
CVE-2020-36228
Published
Jan 25, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-191, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 25, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-191Integer Underflow (Wrap or Wraparound)
T1499.004Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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