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Bug 2019666 (CVE-2021-23192) - CVE-2021-23192 samba: Subsequent DCE/RPC fragment injection vulnerability
Summary: CVE-2021-23192 samba: Subsequent DCE/RPC fragment injection vulnerability
Alias: CVE-2021-23192
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
Depends On: 2019668 2019669 2020164 2021166 2021167 2021715
TreeView+ depends on / blocked
Reported: 2021-11-03 04:06 UTC by Huzaifa S. Sidhpurwala
Modified: 2022-05-17 09:59 UTC (History)
17 users (show)

Fixed In Version: samba 4.15.2, samba 4.14.10, samba 4.13.14
Doc Type: If docs needed, set a value
Doc Text:
A flaw was found in the way samba implemented DCE/RPC. If a client to a Samba server sent a very large DCE/RPC request, and chose to fragment it, an attacker could replace later fragments with their own data, bypassing the signature requirements.
Clone Of:
Last Closed: 2021-11-29 13:09:15 UTC

Attachments (Terms of Use)

System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHBA-2022:0018 0 None None None 2022-01-05 10:32:48 UTC
Red Hat Product Errata RHSA-2021:4843 0 None None None 2021-11-29 12:36:18 UTC
Red Hat Product Errata RHSA-2021:5082 0 None None None 2021-12-13 08:45:26 UTC
Red Hat Product Errata RHSA-2022:0008 0 None None None 2022-01-04 08:21:55 UTC
Samba Project 14875 0 None None None 2021-11-03 14:55:13 UTC

Description Huzaifa S. Sidhpurwala 2021-11-03 04:06:49 UTC
As per upstream advisory:

Samba implements DCE/RPC, and in most cases it is provided over and protected by the underlying SMB transport, with protections like 'SMB signing'.

However there are other cases where large DCE/RPC request payloads are exchanged and fragmented into several pieces. If this happens over untrusted transports (e.g. directly over TCP/IP or anonymous SMB) clients will typically protect by an explicit authentication at the DCE/RPC layer, e.g. with
GSSAPI/Kerberos/NTLMSSP or Netlogn Secure Channel.

Because the checks on the fragment protection were not done between the policy controls on the header and the subsequent fragments, an attacker
could replace subsequent fragments in requests with their own data, which might be able to alter the server behaviour.

Comment 3 Huzaifa S. Sidhpurwala 2021-11-10 02:50:35 UTC
Created samba tracking bugs for this issue:

Affects: fedora-all [bug 2021715]

Comment 4 errata-xmlrpc 2021-11-29 12:36:17 UTC
This issue has been addressed in the following products:

  Red Hat Gluster Storage 3.5 for RHEL 8

Via RHSA-2021:4843

Comment 5 Product Security DevOps Team 2021-11-29 13:09:13 UTC
This bug is now closed. Further updates for individual products will be reflected on the CVE page(s):

Comment 6 Tomas Hoger 2021-12-01 18:36:04 UTC
Upstream advisory:

Comment 7 errata-xmlrpc 2021-12-13 08:45:24 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2021:5082

Comment 8 errata-xmlrpc 2022-01-04 08:21:53 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8.4 Extended Update Support

Via RHSA-2022:0008

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