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6 <title>Samba - Security Announcement Archive</title>
11 <H2>CVE-2020-10760.html:</H2>
15 ===========================================================
16 == Subject: LDAP Use-after-free in Samba AD DC Global Catalog with
17 == paged_results and VLV
19 == CVE ID#: CVE-2020-10760
21 == Versions: All versions of Samba since Samba 4.5.0
23 == Summary: The use of the paged_results or VLV controls against
24 == the Global Catalog LDAP server on the AD DC will cause
26 ===========================================================
32 Samba 4.5 and later implements VLV - Virtual List View, and Samba 4.10
33 and later reimplemented the paged_results control using similar code.
35 This code is more memory-efficient, storing only a pointer to the
36 object, not the returned object. However this means parts of the
37 original request must be retained
39 When these controls are used by a client that connects to the Global
40 Catalog server, these modules failed to correctly retain the control
41 data along with the request, causing a use-after-free and an abort
42 when this is detected by the talloc library.
44 NOTE WELL: Unsupported Samba versions before Samba 4.7 use a single
45 process for the LDAP servers.
47 All versions of Samba after Samba 4.11 use the 'prefork' process model
48 to create a shared connection pool. Crashing servers are restarted,
49 but service is disrupted.
56 Patches addressing both these issues have been posted to:
58 https://www.samba.org/samba/security/
60 Additionally, Samba 4.10.17, 4.11.11 and 4.12.4 have been issued
61 as security releases to correct the defect. Samba administrators are
62 advised to upgrade to these releases or apply the patch as soon
69 CVSS 3.1: AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H (6.5)
71 ================================
72 Workaround and mitigating factors
73 ================================
75 By default, Samba 4.10 is run using the "standard" process model which
76 is one-process-per-client. (Later versions use 'prefork').
78 This is controlled by the -M or --model parameter to the samba binary.
80 All Samba versions are impacted if -M prefork or -M single is used. To
81 mitigate this issue, select -M standard (however this will use more
82 memory, and may cause resource exhaustion).
88 Originally reported by Andrei Popa <andrei.popa@next-gen.ro> and
89 another anonymous reporter.
91 Advisory written by Andrew Bartlett of Catalyst and the Samba Team.
93 Patches provided by Andrew Bartlett of Catalyst and the Samba Team.
95 ==========================================================
96 == Our Code, Our Bugs, Our Responsibility.
98 ==========================================================