CVE-2021-3738: Use After Free
First published: Tue Nov 09 2021(Updated: )
In DCE/RPC it is possible to share the handles (cookies for resource state) between multiple connections via a mechanism called 'association groups'. These handles can reference connections to our sam.ldb database. However while the database was correctly shared, the user credentials state was only pointed at, and when one connection within that association group ended, the database would be left pointing at an invalid 'struct session_info'. The most likely outcome here is a crash, but it is possible that the use-after-free could instead allow different user state to be pointed at and this might allow more privileged access.
Credit: secalert@redhat.com secalert@redhat.com secalert@redhat.com
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Samba Samba | >=4.0.0<4.13.14 | |
| Samba Samba | >=4.14.0<4.14.10 | |
| Samba Samba | >=4.15.0<4.15.2 | |
| redhat/samba | <4.15.2 | 4.15.2 |
| redhat/samba | <4.14.10 | 4.14.10 |
| redhat/samba | <4.13.14 | 4.13.14 |
| ubuntu/samba | <2:4.13.14+dfsg-0ubuntu0.20.04.1 | 2:4.13.14+dfsg-0ubuntu0.20.04.1 |
| ubuntu/samba | <2:4.13.14+dfsg-0ubuntu0.21.04.1 | 2:4.13.14+dfsg-0ubuntu0.21.04.1 |
| ubuntu/samba | <2:4.13.14+dfsg-0ubuntu0.21.10.1 | 2:4.13.14+dfsg-0ubuntu0.21.10.1 |
| ubuntu/samba | <2:4.13.14+dfsg-0ubuntu1 | 2:4.13.14+dfsg-0ubuntu1 |
| ubuntu/samba | <2:4.13.14+dfsg-0ubuntu1 | 2:4.13.14+dfsg-0ubuntu1 |
| ubuntu/samba | <2:4.13.14+dfsg-0ubuntu1 | 2:4.13.14+dfsg-0ubuntu1 |
| ubuntu/samba | <4.13.14 | 4.13.14 |
| debian/samba | <=2:4.9.5+dfsg-5+deb10u3<=2:4.9.5+dfsg-5+deb10u5 | 2:4.13.13+dfsg-1~deb11u5 2:4.13.13+dfsg-1~deb11u6 2:4.17.12+dfsg-0+deb12u1 2:4.19.6+dfsg-1 2:4.19.6+dfsg-3 |
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Reference Links
- https://bugzilla.redhat.com/show_bug.cgi?id=2021726
- https://bugzilla.samba.org/show_bug.cgi?id=14468
- https://security.gentoo.org/glsa/202309-06
- https://www.samba.org/samba/security/CVE-2021-3738.html
- https://launchpad.net/bugs/cve/CVE-2021-3738
- https://bugzilla.redhat.com/show_bug.cgi/show_bug.cgi?id=2021727
- https://security-tracker.debian.org/tracker/CVE-2021-3738
- https://www.samba.org/samba/history/samba-4.13.14.html
- https://ubuntu.com/security/notices/USN-5142-1
- https://www.cve.org/CVERecord?id=CVE-2021-3738
- https://nvd.nist.gov/vuln/detail/CVE-2021-3738
- https://ubuntu.com/security/CVE-2021-3738
Frequently Asked Questions
What is CVE-2021-3738?
CVE-2021-3738 is a vulnerability in DCE/RPC that allows the sharing of handles (cookies for resource state) between multiple connections via association groups.
How does CVE-2021-3738 affect Samba?
CVE-2021-3738 affects Samba versions between 4.0.0 and 4.15.2.
What is the severity of CVE-2021-3738?
The severity of CVE-2021-3738 is high with a CVSS score of 8.8.
How can I fix CVE-2021-3738 in Samba?
To fix CVE-2021-3738 in Samba, update to version 4.15.2 or apply the appropriate patch provided by the vendor.
Where can I find more information about CVE-2021-3738?
More information about CVE-2021-3738 can be found in the following references: [link1], [link2], [link3].
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