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AUSCERT External Security Bulletin Redistribution
ESB-2022.0461
K67416037: Linux kernel vulnerability CVE-2021-23133
3 February 2022
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AusCERT Security Bulletin Summary
---------------------------------
Product: BIG-IP (all modules)
BIG-IQ Centralized Management
Traffix SDC
Publisher: F5 Networks
Operating System: Network Appliance
Resolution: Mitigation
CVE Names: CVE-2021-23133
Reference: ESB-2021.3825
Original Bulletin:
https://support.f5.com/csp/article/K67416037
Comment: CVSS (Max): 7.0 CVE-2021-23133 (CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H)
CVSS Source: F5 Networks
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K67416037: Linux kernel vulnerability CVE-2021-23133
Original Publication Date: 03 Feb, 2022
Security Advisory Description
A race condition in Linux kernel SCTP sockets (net/sctp/socket.c) before
5.12-rc8 can lead to kernel privilege escalation from the context of a network
service or an unprivileged process. If sctp_destroy_sock is called without
sock_net(sk)->sctp.addr_wq_lock then an element is removed from the
auto_asconf_splist list without any proper locking. This can be exploited by an
attacker with network service privileges to escalate to root or from the
context of an unprivileged user directly if a BPF_CGROUP_INET_SOCK_CREATE is
attached which denies creation of some SCTP socket. (CVE-2021-23133)
Impact
An attacker may be able to exploit this vulnerability to disclosure sensitive
information, modify data, or cause a Denial of Service (DoS).
Security Advisory Status
F5 Product Development has assigned ID 1077301 (BIG-IP and BIG-IQ) and
SDC-1683 (Traffix SDC) to this vulnerability.
To determine if your product and version have been evaluated for this
vulnerability, refer to the Applies to (see versions) box. To determine if your
release is known to be vulnerable, the components or features that are affected
by the vulnerability, and for information about releases, point releases, or
hotfixes that address the vulnerability, refer to the following table. For more
information about security advisory versioning, refer to K51812227:
Understanding security advisory versioning.
Note: After a fix is introduced for a given minor branch, that fix applies to
all subsequent maintenance and point releases for that branch, and no
additional fixes for that branch will be listed in the table. For example, when
a fix is introduced in 14.1.2.3, the fix also applies to 14.1.2.4, and all
later 14.1.x releases (14.1.3.x., 14.1.4.x). For more information, refer to
K51812227: Understanding security advisory versioning. Additionally, software
versions preceding those listed in the Applies to (see versions) box of this
article have reached the End of Technical Support (EoTS) phase of their
lifecycle and are no longer evaluated for security issues. For more
information, refer to the Security hotfixes section of K4602: Overview of the
F5 security vulnerability response policy.
+------------+------+--------------+----------+----------+------+-------------+
| | |Versions known|Fixes | |CVSSv3|Vulnerable |
|Product |Branch|to be |introduced|Severity |score^|component or |
| | |vulnerable^1 |in | |2 |feature |
+------------+------+--------------+----------+----------+------+-------------+
| |16.x |16.1.0 - |None | | | |
| | |16.1.2 | | | | |
| +------+--------------+----------+ | | |
| |15.x |15.1.0 - |None | | | |
| | |15.1.5 | | | | |
| +------+--------------+----------+ | | |
| |14.x |14.1.0 - |None | | | |
|BIG-IP (all | |14.1.4 | | | | |
|modules) +------+--------------+----------+High |7.0 |Linux kernel |
| |13.x |13.1.0 - |None | | | |
| | |13.1.4 | | | | |
| +------+--------------+----------+ | | |
| |12.x |None |Not | | | |
| | | |applicable| | | |
| +------+--------------+----------+ | | |
| |11.x |None |Not | | | |
| | | |applicable| | | |
+------------+------+--------------+----------+----------+------+-------------+
|BIG-IQ |8.x |8.0.0 - 8.1.0 |None | | | |
|Centralized +------+--------------+----------+High |7.0 |Linux kernel |
|Management |7.x |None |Not | | | |
| | | |applicable| | | |
+------------+------+--------------+----------+----------+------+-------------+
|F5OS-A |1.x |None |Not |Not |None |None |
| | | |applicable|vulnerable| | |
+------------+------+--------------+----------+----------+------+-------------+
|F5OS-C |1.x |None |Not |Not |None |None |
| | | |applicable|vulnerable| | |
+------------+------+--------------+----------+----------+------+-------------+
|Traffix SDC |5.x |5.2.0 |None |High |7.0 |Linux kernel |
+------------+------+--------------+----------+----------+------+-------------+
^1F5 evaluates only software versions that have not yet reached the End of
Technical Support (EoTS) phase of their lifecycle.
^2The CVSSv3 score link takes you to a resource outside of AskF5, and it is
possible that the document may be removed without our knowledge.
Recommended Actions
If you are running a version listed in the Versions known to be vulnerable
column, you can eliminate this vulnerability by installing a version listed in
the Fixes introduced in column. If the Fixes introduced in column does not list
a version for your branch, then no update candidate currently exists for that
branch and F5 recommends upgrading to a version with the fix (refer to the
table).
If the Fixes introduced in column lists a version prior to the one you are
running, in the same branch, then your version should have the fix.
Mitigation
BIG-IP and BIG-IQ
BIG-IP and BIG-IQ systems do not load the SCTP kernel module by default so the
risk from this vulnerability is mitigated in default, standard, or recommended
configurations.
Traffix SDC
There is no mitigation for Traffix SDC.
Supplemental Information
o K41942608: Overview of security advisory articles
o K4602: Overview of the F5 security vulnerability response policy
o K4918: Overview of the F5 critical issue hotfix policy
o K8986: F5 software lifecycle policy
o K9502: BIG-IP hotfix and point release matrix
o K13123: Managing BIG-IP product hotfixes (11.x - 16.x)
o K15106: Managing BIG-IQ product hotfixes
o K15113: BIG-IQ hotfix and point release matrix
o K167: Downloading software and firmware from F5
o K9970: Subscribing to email notifications regarding F5 products
o K9957: Creating a custom RSS feed to view new and updated documents
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