Use After Free in Linux
CVE-2021-47111
In the Linux kernel, the following vulnerability has been resolved: xen-netback: take a reference to the RX task thread Do this in order to prevent the task from being freed if the thread returns (which can be triggered by the frontend) before the call to kthread_stop done as part of the backend tear down. Not taking the reference will lead to a use-after-free in that scenario. Such reference was taken before but dropped as part of the rework done in 2ac061ce97f4. Reintroduce the reference taking and add a comment this time explaining why it's needed. This is XSA-374 / CVE-2021-28691.
Vulnerability class: Use-After-Free
EPSS: 0.002 (14.5th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H.
Affected products
- Linux — versions 2ac061ce97f413bfbbdd768f7d2e0fda2e8170df, 5.5, 0
- Linux Linux_kernel — versions 5.13
Weakness classification (CWE)
Public proof-of-concept exploits
References
Frequently asked questions
- What is CVE-2021-47111?
- CVE-2021-47111 is a high-severity vulnerability in Linux, classified under Use After Free. CVSS score: 8.8/10. Published 2024-03-15.
- How severe is CVE-2021-47111?
- High severity. CVSS v3 base score is 8.8 out of 10.
- Is CVE-2021-47111 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.