CVE-2020-12243Public exploitNetwork attack vector

Unauthenticated daemon crash via deeply nested filters

Published Apr 28, 2020 · Updated Aug 4, 2024

Uncontrolled recursion in slapd in OpenLDAP before 2.4.50 allows remote attackers to crash the LDAP daemon via a deeply nested search filter. The filter parser recursively processes nested Boolean expressions without a depth limit, allowing tens of thousands of nested OR clauses to exhaust the process stack. No authentication or user interaction is required when an attacker can submit LDAP searches; exploitation interrupts directory service availability by crashing slapd.

CVSS severity7.5
High
EPSS probability4.42%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Uncontrolled recursion in slapd in OpenLDAP before 2.4.50 allows remote attackers to crash the LDAP daemon via a deeply nested search filter. The filter parser recursively processes nested Boolean expressions without a depth limit, allowing tens of thousands of nested OR clauses to exhaust the process stack. No authentication or user interaction is required when an attacker can submit LDAP searches; exploitation interrupts directory service availability by crashing slapd.

The record

CVE
CVE-2020-12243
Published
Apr 28, 2020
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-674, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 28, 2020CVE 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

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

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-674Uncontrolled Recursion
T1499.004Endpoint Denial of Service: Application 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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