boxscore/security
CVE · referencelatest edition

Reference page — cumulative record through Wednesday, August 19, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.

CVE-2021-47281HIGH
Linux Linux — ALSA: seq: Fix race of snd_seq_timer_open()
  AV  AC  PR  UI  S  C  I  A   CVSS    EPSS   %ile   KEV
   L   H   L   N  U  H  H  H    7.0   .0024   15.0     —
AFFECTED
  Product  Versions                                    Fixed
  Linux    1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 –  —
  Linux    2.6.12 –                                    5.10.44
TIMELINE
  May 21  Reserved by Linux
  May 21  Published (CNA: Linux)
  Aug 4   RESCORED — CVE-2021-47281 (Linux). CVSS 7.8 → 7 (NVD).
CWE-416 · CNA: Linux · CVSS v3.1 · 3 references · NVD status: Modified

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.

Lifecycle

Complete event history — 3 events, chronological
DateEventDetail
May 21, 2024ReservedReserved by Linux
May 21, 2024PublishedPublished (CNA: Linux)
August 4, 2026RESCOREDRESCORED — CVE-2021-47281 (Linux). CVSS 7.8 → 7 (NVD).

Affected

Affected products and packages — 2 rows
VendorProduct / PackageEcosystemVersion introducedFixed
LinuxLinux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
LinuxLinux2.6.125.10.44

Weaknesses

CWE-416

References (3)

Related

Authoritative record: CVE-2021-47281 at cve.org

Vendors: linux

Weaknesses: CWE-416

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2021-47281 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Wednesday, August 19, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.