1 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
2 "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
3 <html xmlns="http://www.w3.org/1999/xhtml">
6 <title>Samba - Security Announcement Archive</title>
11 <H2>CVE-2020-14383.html:</H2>
15 ===========================================================
16 == Subject: An authenticated user can crash the DCE/RPC DNS with
17 == easily crafted records
19 == CVE ID#: CVE-2020-14383
21 == Versions: Samba 4.0 and later
23 == Summary: An authenticated non-admin user can crash the
24 == DNS server by adding invalid records.
25 ===========================================================
31 Some DNS records (such as MX and NS records) usually contain data in
32 the additional section. Samba's dnsserver RPC pipe (which is an
33 administrative interface not used in the DNS server itself) made an
34 error in handling the case where there are no records present: instead
35 of noticing the lack of records, it dereferenced uninitialised memory,
36 causing the RPC server to crash. This RPC server, which also serves
37 protocols other than dnsserver, will be restarted after a short delay,
38 but it is easy for an authenticated non-admin attacker to crash it
39 again as soon as it returns. The Samba DNS server itself will continue
40 to operate, but many RPC services will not.
46 Patches addressing both these issues have been posted to:
48 https://www.samba.org/samba/security/
50 Additionally, Samba 4.11.15, 4.12.9 and 4.13.1 have been issued
51 as security releases to correct the defect. Samba administrators are
52 advised to upgrade to these releases or apply the patch as soon
59 CVSSv3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H (6.5)
65 The dnsserver task can be stopped by setting
67 'dcerpc endpoint servers = -dnsserver'
69 in the smb.conf and restarting Samba.
75 Originally reported by Francis Brosnan Blázquez of ASPL.es in 2017.
77 Patches first provided for Samba 4.6 by Francis Brosnan Blázquez, and
78 adapted for modern Samba by Douglas Bagnall of the Samba team.
80 ==========================================================
81 == Our Code, Our Bugs, Our Responsibility.
83 ==========================================================