CVE-2020-27840Network attack vector

Unauthenticated LDAP heap corruption crash

Published May 12, 2021 · Updated Aug 4, 2024

Heap corruption in Samba AD DC LDAP server 4.14.1, 4.13.6 and 4.12.13 allows remote attackers to crash it via crafted DN bind requests. The DN parser treats spaces around domain-name components incorrectly and writes a zero byte at a negative offset outside a heap buffer before password validation. An unauthenticated attacker can send the malformed bind remotely; the likely result is LDAP service termination, while more extensive heap corruption is possible but not established.

CVSS severity7.5
High
EPSS probability3.83%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap corruption in Samba AD DC LDAP server 4.14.1, 4.13.6 and 4.12.13 allows remote attackers to crash it via crafted DN bind requests. The DN parser treats spaces around domain-name components incorrectly and writes a zero byte at a negative offset outside a heap buffer before password validation. An unauthenticated attacker can send the malformed bind remotely; the likely result is LDAP service termination, while more extensive heap corruption is possible but not established.

The record

CVE
CVE-2020-27840
Published
May 12, 2021
Updated
Aug 4, 2024
Vendor
PPP Project
Product
Samba
Classifications
CWE-787, T1499.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 12, 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?

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

5.0NVDAV:N/AC:L/Au:N/C:N/I:N/A:P
7.5Samba TeamCVSS: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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 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
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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