VulnerabilityModified

CVE-2021-47281

HIGH 7.0EPSS 0.24%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (0.24%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

Description

In the Linux kernel, the following vulnerability has been resolved: ALSA: seq: Fix race of snd_seq_timer_open() The timer instance per queue is exclusive, and snd_seq_timer_open() should have managed the concurrent accesses. It looks as if it's checking the already existing timer instance at the beginning, but it's not right, because there is no protection, hence any later concurrent call of snd_seq_timer_open() may override the timer instance easily. This may result in UAF, as the leftover timer instance can keep running while the queue itself gets closed, as spotted by syzkaller recently. For avoiding the race, add a proper check at the assignment of tmr->timeri again, and return -EBUSY if it's been already registered.

CVSS 3.1: 7.0 HIGHCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS: 0.24% probability · 15th percentile
Public exploits: None in Exploit-DB
CISA KEV: Not listed
Weakness: CWE-416
Affected: linux/linux kernel
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67

EPSS trend

EPSS 0.2% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.

References

Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.