CVE-2021-20277Network attack vector

Unauthenticated LDAP filter crash via memmove

Published May 12, 2021 · Updated Aug 3, 2024

Out-of-bounds read in libldb in PPP Project Samba 4.14.1, 4.13.6 and 4.12.13 allows remote attackers to crash the LDAP server via crafted filters. The ldb_handler_fold() routine normalizes case-insensitive LDAP attributes with memmove() and mishandles multiple leading spaces, reading or writing beyond the buffer. The request requires network access to the AD DC LDAP service; impact is primarily service interruption, with memory disclosure considered unlikely.

CVSS severity7.5
High
EPSS probability4.33%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds read in libldb in PPP Project Samba 4.14.1, 4.13.6 and 4.12.13 allows remote attackers to crash the LDAP server via crafted filters. The ldb_handler_fold() routine normalizes case-insensitive LDAP attributes with memmove() and mishandles multiple leading spaces, reading or writing beyond the buffer. The request requires network access to the AD DC LDAP service; impact is primarily service interruption, with memory disclosure considered unlikely.

The record

CVE
CVE-2021-20277
Published
May 12, 2021
Updated
Aug 3, 2024
Vendor
PPP Project
Product
Samba
Classifications
CWE-787, CWE-125, T1499.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 12, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=samba 4.14.1, samba 4.13.6, samba 4.12.13

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

PPP Project · Sambaversion=samba 4.14.1, samba 4.13.6, samba 4.12.13

Published CVSS scores

7.5NVDCVSS: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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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 exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write
CWE-125Out-of-bounds Read
T1499.002Endpoint Denial of Service: Service Exhaustion

Public exploit references

No public exploit references are available in this record.

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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