CVE-2026-64479

ALSA: seq: Fix uninitialised heap leak in snd_seq_event_dup()

Published Jul 25, 2026 CVSS 3.1 · 3.3 Low EPSS < 1% KEV · Not listed

Description

In the Linux kernel, the following vulnerability has been resolved:

ALSA: seq: Fix uninitialised heap leak in snd_seq_event_dup()

snd_seq_event_dup() copies an incoming event into a pool cell and, in
the UMP-enabled build, clears the trailing cell->ump.raw.extra word that
the memcpy() did not cover. The guard deciding whether to clear it
compares the copied size against sizeof(cell->event):

memcpy(&cell->ump, event, size);
if (size < sizeof(cell->event))
cell->ump.raw.extra = 0;

For a legacy (non-UMP) event, size == sizeof(struct snd_seq_event) ==
sizeof(cell->event), so the condition is false and the extra word keeps
stale data. The cell pool is allocated with kvmalloc() (not zeroed) and
cells are reused via a free list, so that word holds uninitialised heap
or leftover event data.

When such a cell is delivered to a UMP client (client->midi_version > 0)
that set SNDRV_SEQ_FILTER_NO_CONVERT -- so the legacy event reaches it
unconverted -- snd_seq_read() reads it out as the larger struct
snd_seq_ump_event and copies the stale word to user space, a 4-byte
kernel heap infoleak to an unprivileged /dev/snd/seq client.

Compare against sizeof(cell->ump) instead, so the trailing word is zeroed
for every event shorter than the UMP cell.

Affected Products

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

Linux

unaffected

Version	Status	Constraints
`6389f2c135311c4ce7c08c3b29145c8f95aacf1f`	affected	< d7649aa11089a93ea2285c210397aa67e5800766
`d7e2ce72833bb23a82b4201fbed7214cc04a4a8c`	affected	< a224c84e5d3d35708c082c84ad12d81d90762195
`46397622a3fa8372b8fda0f04b33d16923b03b1b`	affected	< ea672a9f6cc38f06fe69dd2c257ef8a3d4db179a
`46397622a3fa8372b8fda0f04b33d16923b03b1b`	affected	< fb1aa5082847b98f44f9c6272aee9d0dca9244f0
`46397622a3fa8372b8fda0f04b33d16923b03b1b`	affected	< 651ba82fe2a144bc7356d940bfd235c3810b0549
`46397622a3fa8372b8fda0f04b33d16923b03b1b`	affected	< 6ded42615fa1f4949925afd0a8a9e1ab3bf96202
`46397622a3fa8372b8fda0f04b33d16923b03b1b`	affected	< 435990e25bf1f4af3e6df12a6fbfd1f7ba4a97d4

Linux

affected

Version	Status	Constraints
`6.5`	affected	—
`0`	unaffected	< 6.5
`6.6.145`	unaffected	≤ 6.6.*
`6.12.96`	unaffected	≤ 6.12.*
`6.18.39`	unaffected	≤ 6.18.*
`7.1.4`	unaffected	≤ 7.1.*
`7.2`	unaffected	≤ *

Configuration 1 [-]

OR	cpe:2.3:o:linux:linux_kernel::::::::
	cpe:2.3:o:linux:linux_kernel::::::::
	cpe:2.3:o:linux:linux_kernel::::::::
	cpe:2.3:o:linux:linux_kernel::::::::

No data.

Vendor Product Versions

Linux

Linux Kernel

Version	Status	Scheme	Platform
`[6389f2c135311c4ce7c08c3b29145c8f95aacf1f,d7649aa11089a93ea2285c210397aa67e5800766)`	affected	code_commit	—
`[d7e2ce72833bb23a82b4201fbed7214cc04a4a8c,a224c84e5d3d35708c082c84ad12d81d90762195)`	affected	code_commit	—
`[46397622a3fa8372b8fda0f04b33d16923b03b1b,ea672a9f6cc38f06fe69dd2c257ef8a3d4db179a)`	affected	code_commit	—
`[46397622a3fa8372b8fda0f04b33d16923b03b1b,fb1aa5082847b98f44f9c6272aee9d0dca9244f0)`	affected	code_commit	—
`[46397622a3fa8372b8fda0f04b33d16923b03b1b,651ba82fe2a144bc7356d940bfd235c3810b0549)`	affected	code_commit	—
`[46397622a3fa8372b8fda0f04b33d16923b03b1b,6ded42615fa1f4949925afd0a8a9e1ab3bf96202)`	affected	code_commit	—
`[46397622a3fa8372b8fda0f04b33d16923b03b1b,435990e25bf1f4af3e6df12a6fbfd1f7ba4a97d4)`	affected	code_commit	—

Linux

Linux Kernel

Version	Status	Scheme	Platform
`6.5`	affected	semver	—
`[0,6.5)`	unaffected	semver	—
`[6.6.145,6.7.0)`	unaffected	semver	—
`[6.12.96,6.13.0)`	unaffected	semver	—
`[6.18.39,6.19.0)`	unaffected	semver	—
`[7.1.4,7.2.0)`	unaffected	semver	—
`[0,*]`	unaffected	generic	—

Remediation

No solution or workaround provided in the CVE record

Tracking

Advisories

Source	ID	Title
Debian DLA	DLA-4724-1	linux-6.12 new package
Ubuntu USN	USN-8726-1	Linux kernel vulnerabilities
Ubuntu USN	USN-8727-1	Linux kernel (OEM) vulnerabilities
Ubuntu USN	USN-8728-1	Linux kernel (GCP) vulnerabilities
Ubuntu USN	USN-8760-1	Linux kernel (NVIDIA) vulnerabilities
Ubuntu USN	USN-8726-2	Linux kernel (Raspberry Pi) vulnerabilities
Ubuntu USN	USN-8726-3	Linux kernel (IBM) vulnerabilities
Ubuntu USN	USN-8800-1	Linux kernel (NVIDIA BaseOS) vulnerabilities
Ubuntu USN	USN-8760-2	Linux kernel (NVIDIA) vulnerabilities
Ubuntu USN	USN-8726-4	Linux kernel vulnerabilities
Ubuntu USN	USN-8728-2	Linux kernel (Azure) vulnerabilities
Ubuntu USN	USN-8728-3	Linux kernel (Oracle) vulnerabilities
Ubuntu USN	USN-8917-1	Linux kernel vulnerabilities
Ubuntu USN	USN-8918-1	Linux kernel (Azure) vulnerabilities
Ubuntu USN	USN-9024-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9025-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9026-1	Linux kernel (Azure) vulnerabilities
Ubuntu USN	USN-9040-1	Linux kernel (Low Latency NVIDIA) vulnerabilities
Ubuntu USN	USN-9066-1	Linux kernel (HWE) vulnerabilities
Ubuntu USN	USN-9091-1	Linux kernel (NVIDIA Tegra) vulnerabilities

Metrics

No CVSS v4.0

Attack Vector Local

Attack Complexity Low

Privileges Required Low

Scope Unchanged

Confidentiality Impact Low

Integrity Impact None

Availability Impact None

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Exploit prediction score: < 1% (0.181% probability within 30 days)

Exploitation none

Automatable no

Technical Impact partial

References

Link	Providers
https://git.kernel.org/stable/c/435990e25bf1f4af3e6df12a6fbfd1f7ba4a97d4
https://git.kernel.org/stable/c/651ba82fe2a144bc7356d940bfd235c3810b0549
https://git.kernel.org/stable/c/6ded42615fa1f4949925afd0a8a9e1ab3bf96202
https://git.kernel.org/stable/c/a224c84e5d3d35708c082c84ad12d81d90762195
https://git.kernel.org/stable/c/d7649aa11089a93ea2285c210397aa67e5800766
https://git.kernel.org/stable/c/ea672a9f6cc38f06fe69dd2c257ef8a3d4db179a
https://git.kernel.org/stable/c/fb1aa5082847b98f44f9c6272aee9d0dca9244f0
https://lore.kernel.org/linux-cve-announce/2026072547-CVE-2026-64479-d0d2@gregkh/T
https://nvd.nist.gov/vuln/detail/CVE-2026-64479
https://www.cve.org/CVERecord?id=CVE-2026-64479

History

Nov 12, 2026 4:30 PM Scoring metrics updated View changes

Type	Values Removed	Values Added
Metrics	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'}`	cvssV3_1 `{'score': 3.3, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N'}`

Nov 7, 2026 7:30 AM Scoring metrics updated View changes

Type	Values Removed	Values Added
Metrics		ssvc `{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}`

Aug 1, 2026 1:45 AM Weaknesses updated View changes

Type	Values Removed	Values Added
Weaknesses	CWE-788

Jul 28, 2026 12:15 AM Weaknesses updated. Added references. Scoring metrics updated View changes

Type	Values Removed	Values Added
Weaknesses		CWE-908
References		https://lore.kernel.org/linux-cve-announce/2026072547-CVE-2026-64479-d0d2@gregkh/T https://nvd.nist.gov/vuln/detail/CVE-2026-64479 https://www.cve.org/CVERecord?id=CVE-2026-64479
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`

Jul 26, 2026 1:30 AM Weaknesses updated View changes

Type	Values Removed	Values Added
Weaknesses		CWE-788

Jul 25, 2026 9:30 AM Description updated. Title updated. First appearance in the feed. Affected versions updated. Affected vendors updated. Added references View changes

Type	Values Removed	Values Added
Description		In the Linux kernel, the following vulnerability has been resolved: ALSA: seq: Fix uninitialised heap leak in snd_seq_event_dup() snd_seq_event_dup() copies an incoming event into a pool cell and, in the UMP-enabled build, clears the trailing cell->ump.raw.extra word that the memcpy() did not cover. The guard deciding whether to clear it compares the copied size against sizeof(cell->event): memcpy(&cell->ump, event, size); if (size < sizeof(cell->event)) cell->ump.raw.extra = 0; For a legacy (non-UMP) event, size == sizeof(struct snd_seq_event) == sizeof(cell->event), so the condition is false and the extra word keeps stale data. The cell pool is allocated with kvmalloc() (not zeroed) and cells are reused via a free list, so that word holds uninitialised heap or leftover event data. When such a cell is delivered to a UMP client (client->midi_version > 0) that set SNDRV_SEQ_FILTER_NO_CONVERT -- so the legacy event reaches it unconverted -- snd_seq_read() reads it out as the larger struct snd_seq_ump_event and copies the stale word to user space, a 4-byte kernel heap infoleak to an unprivileged /dev/snd/seq client. Compare against sizeof(cell->ump) instead, so the trailing word is zeroed for every event shorter than the UMP cell.
Title		ALSA: seq: Fix uninitialised heap leak in snd_seq_event_dup()
First Time appeared		Linux Linux linux Kernel
CPEs		cpe:2.3:o:linux:linux_kernel::::::::
Vendors & Products		Linux Linux linux Kernel
References		https://git.kernel.org/stable/c/435990e25bf1f4af3e6df12a6fbfd1f7ba4a97d4 https://git.kernel.org/stable/c/651ba82fe2a144bc7356d940bfd235c3810b0549 https://git.kernel.org/stable/c/6ded42615fa1f4949925afd0a8a9e1ab3bf96202 https://git.kernel.org/stable/c/a224c84e5d3d35708c082c84ad12d81d90762195 https://git.kernel.org/stable/c/d7649aa11089a93ea2285c210397aa67e5800766 https://git.kernel.org/stable/c/ea672a9f6cc38f06fe69dd2c257ef8a3d4db179a https://git.kernel.org/stable/c/fb1aa5082847b98f44f9c6272aee9d0dca9244f0