CVE-2021-43389: Out-of-bounds Read
An improper validation of an array index and out of bounds memory read in the Linux kernel's Integrated Services Digital Network (ISDN) functionality was found in the way users call ioctl CMTPCONNADD. A local user could use this flaw to crash the system or starve the resources causing denial of service.
Other sources
An issue was discovered in the Linux kernel before 5.14.15. There is an array-index-out-of-bounds flaw in the detachcapictr function in drivers/isdn/capi/kcapi.c.
There is an array-index-out-bounds bug in detachcapictr in drivers/isdn/capi/kcapi.c. During this process, the kernel thread would call detachcapictr() to detach a register controller. if the controller was not attached yet, detachcapictr() would trigger an array-index-out-bounds bug.
Reference:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=1f3e2e97c003f80c4b087092b225c8787ff91e4d https://lore.kernel.org/netdev/CAFcO6XOvGQrRTaTkaJ0p3zR7y7nrAWD79r48=LBbOyrK9X-vA@mail.gmail.com/
— Red Hat
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
redhat/kernel-rtto a version that resolves this vulnerability.Fixed in 0:4.18.0-372.9.1.rt7.166.el8 - Upgrade
Upgrade
redhat/kernelto a version that resolves this vulnerability.Fixed in 0:4.18.0-372.9.1.el8 - Upgrade
Upgrade
debian/linuxto a version that resolves this vulnerability.Fixed in 5.10.223-1Fixed in 5.10.234-1Fixed in 6.1.129-1Fixed in 6.1.135-1Fixed in 6.12.25-1Fixed in 6.12.27-1 - Upgrade
Upgrade
redhat/Linux kernelto a version that resolves this vulnerability.Fixed in 5.15 - Upgrade
Upgrade
Linux kernelto a version that resolves this vulnerability.Fixed in 5.14.15 - Configuration
Prevent the isdn kernel module from being loaded automatically.
Linux kernel isdn module module loading = blacklisted/disabled
Event History
Parent advisories
This vulnerability appears in the following advisories.
Frequently Asked Questions
What is the severity of CVE-2021-43389?
CVE-2021-43389 has a severity rating that may allow local users to crash the system or cause denial of service.
How do I fix CVE-2021-43389?
To fix CVE-2021-43389, update to kernel-rt version 0:4.18.0-372.9.1.rt7.166.el8 or kernel version 0:4.18.0-372.9.1.el8.
Which systems are affected by CVE-2021-43389?
CVE-2021-43389 affects multiple Linux kernel versions and specific distributions such as Red Hat Enterprise Linux and Debian.
Can CVE-2021-43389 be exploited remotely?
CVE-2021-43389 is a local vulnerability, meaning it requires local access to exploit.
What versions of the Linux kernel are vulnerable to CVE-2021-43389?
Linux kernel versions up to 5.14.15 are vulnerable to CVE-2021-43389.