CVE-2021-47356

CVE-2021-47356 is a high-severity vulnerability in Linux Linux Kernel with a CVSS 3.x base score of 7.7. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-416.

Key facts

Description

In the Linux kernel, the following vulnerability has been resolved: mISDN: fix possible use-after-free in HFC_cleanup() This module's remove path calls del_timer(). However, that function does not wait until the timer handler finishes. This means that the timer handler may still be running after the driver's remove function has finished, which would result in a use-after-free. Fix by calling del_timer_sync(), which makes sure the timer handler has finished, and unable to re-schedule itself.

Frequently asked questions

What is CVE-2021-47356?
In the Linux kernel, the following vulnerability has been resolved: mISDN: fix possible use-after-free in HFC_cleanup() This module's remove path calls del_timer(). However, that function does not wait until the timer handler finishes. This means that the timer handler may still be running after the driver's remove function has finished, which would result in a use-after-free. Fix by calling del_timer_sync(), which makes sure the timer handler has finished, and unable to re-schedule itself.
How severe is CVE-2021-47356?
CVE-2021-47356 has a CVSS 3.x base score of 7.7, rated high severity. It is exploitable over local access with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability high.
Is CVE-2021-47356 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (18th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-47356?
CVE-2021-47356 affects Linux Linux Kernel. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-47356?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2021-47356 have an EU (EUVD) identifier?
Yes. CVE-2021-47356 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2021-34361.
When was CVE-2021-47356 published?
CVE-2021-47356 was published on 2024-05-21 and last updated on 2026-06-17.

References

Affected products (1)

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