CVE-2021-3738Network attack vector

Service crash or privilege escalation via freed credentials

Published Mar 2, 2022 · Updated Aug 3, 2024

Use-after-free in affected Samba 4.0 and later AD DC RPC servers allows remote authenticated users to crash the service. DCE/RPC association groups share sam.ldb handles across connections, but a closed sub-connection leaves the database pointing to freed struct session_info credentials. An authenticated AD DC client can trigger a server crash; reused memory can instead bind another user's state and grant greater privileges.

CVSS severity7.6
High
EPSS probability1.92%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in affected Samba 4.0 and later AD DC RPC servers allows remote authenticated users to crash the service. DCE/RPC association groups share sam.ldb handles across connections, but a closed sub-connection leaves the database pointing to freed struct session_info credentials. An authenticated AD DC client can trigger a server crash; reused memory can instead bind another user's state and grant greater privileges.

The record

CVE
CVE-2021-3738
Published
Mar 2, 2022
Updated
Aug 3, 2024
Vendor
PPP Project
Product
Samba
Classifications
CWE-416, T1210
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 2, 2022CVE 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=Affects all versions since samba 4.0 | Fixedin samba v4.15.2, v4.14.10 and v4.13.14

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

PPP Project · Sambaversion=Affects all versions since samba 4.0 | Fixedin samba v4.15.2, v4.14.10 and v4.13.14

Published CVSS scores

8.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
7.6Samba TeamCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:H
6.5NIST NVDAV:N/AC:L/Au:S/C:P/I:P/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.

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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free
T1210Exploitation of Remote Services

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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