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Vulnerability record · CVE-2021-28951 · published 20 March 2021

CVE-2021-28951: Linux kernel vulnerability

Linux · Linux Kernel

An issue was discovered in fs/io_uring.c in the Linux kernel through 5.11.8. It allows attackers to cause a denial of service (deadlock) because exit may be waiting to park a SQPOLL thread, but concurrently that SQPOLL thread is waiting for a signal to start, aka CID-3ebba796fa25.

5.5 CVSS 3.1 Medium EPSS 0.28% · top 81.7% CWE-667 · CWE-667
5.5CVSS 3.1 base score, v2 4.9
0.28%EPSS exploitation probability, 30 days
NoNot in CISA KEV
7Affected product versions listed by NVD
10References
17 Jun 2026Last modified by NVD

Description

An issue was discovered in fs/io_uring.c in the Linux kernel through 5.11.8. It allows attackers to cause a denial of service (deadlock) because exit may be waiting to park a SQPOLL thread, but concurrently that SQPOLL thread is waiting for a signal to start, aka CID-3ebba796fa25.

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products

7 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3ebba796fa251d042be42b929a2d916ee5c34a49 PatchVendor Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/4VCKIOXCOZGXBEZMO5LGGV5
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PTRNPQTZ4GVS46SZ4OBXY5Y
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/T2S3I4SLRNRUQDOFYUS6IUA
https://security.netapp.com/advisory/ntap-20210430-0003/ Third Party Advisory
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3ebba796fa251d042be42b929a2d916ee5c34a49 PatchVendor Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/4VCKIOXCOZGXBEZMO5LGGV5
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PTRNPQTZ4GVS46SZ4OBXY5Y
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/T2S3I4SLRNRUQDOFYUS6IUA
https://security.netapp.com/advisory/ntap-20210430-0003/ Third Party Advisory

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2021-28951), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.