CVE-2026-53241

ALSA: seq: dummy: fix UMP event stack overread

Published Jun 25, 2026 CVSS 3.1 · 5.5 Medium EPSS < 1% KEV · Not listed
Description
In the Linux kernel, the following vulnerability has been resolved:

ALSA: seq: dummy: fix UMP event stack overread

The dummy sequencer port forwards events by copying an incoming
struct snd_seq_event into a stack temporary, rewriting source and
destination, and dispatching the temporary to subscribers. That legacy
event storage is smaller than struct snd_seq_ump_event.

When a UMP event reaches the dummy client, the copy leaves the UMP flag
set but only provides legacy-sized stack storage. The subscriber
delivery path then uses snd_seq_event_packet_size() and copies a
UMP-sized packet from that stack object, reading past the end of the
temporary.

Use the existing union __snd_seq_event storage and copy the packet size
reported for the incoming event before rewriting the common routing
fields. This preserves the full UMP packet for UMP events while keeping
legacy event handling unchanged.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Ubuntu USN Ubuntu USN USN-8726-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-8727-1 Linux kernel (OEM) vulnerabilities
Ubuntu USN Ubuntu USN USN-8728-1 Linux kernel (GCP) vulnerabilities
Ubuntu USN Ubuntu USN USN-8760-1 Linux kernel (NVIDIA) vulnerabilities
Ubuntu USN Ubuntu USN USN-8726-2 Linux kernel (Raspberry Pi) vulnerabilities
Ubuntu USN Ubuntu USN USN-8726-3 Linux kernel (IBM) vulnerabilities
Ubuntu USN Ubuntu USN USN-8800-1 Linux kernel (NVIDIA BaseOS) vulnerabilities
Ubuntu USN Ubuntu USN USN-8760-2 Linux kernel (NVIDIA) vulnerabilities
Ubuntu USN Ubuntu USN USN-8726-4 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-8728-2 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-8728-3 Linux kernel (Oracle) vulnerabilities
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Weaknesses CWE-839
Type Values Removed Values Added
References
Metrics threat_severity

None

cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Moderate

Type Values Removed Values Added
Weaknesses CWE-125
CWE-839
Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: ALSA: seq: dummy: fix UMP event stack overread The dummy sequencer port forwards events by copying an incoming struct snd_seq_event into a stack temporary, rewriting source and destination, and dispatching the temporary to subscribers. That legacy event storage is smaller than struct snd_seq_ump_event. When a UMP event reaches the dummy client, the copy leaves the UMP flag set but only provides legacy-sized stack storage. The subscriber delivery path then uses snd_seq_event_packet_size() and copies a UMP-sized packet from that stack object, reading past the end of the temporary. Use the existing union __snd_seq_event storage and copy the packet size reported for the incoming event before rewriting the common routing fields. This preserves the full UMP packet for UMP events while keeping legacy event handling unchanged.
Title ALSA: seq: dummy: fix UMP event stack overread
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
Linux
Published
Updated
Nov 6, 2026, 4:24 PM
Reserved
Jun 9, 2026, 7:44 AM
Status
Analyzed
Published
Jun 25, 2026, 9:16 AM
Modified
Nov 6, 2026, 5:18 PM
Severity
Moderate
Public date
Jun 25, 2026, 12:00 AM