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NVD / CVE Program· CNA Linux

CVE-2026-74387: ALSA: seq: midi: Serialize output teardown with event_input

Noroxi assessment

Priority: Monitor (action score 31/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.17% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 11165fe2c5ea0516debe486d91df67abbe36905e, 718f6a56b40875f19e6915799044a02df9abfd52, 936641af564c3d92721704b781e36aaf223efdd2.

Low priority for now. Upgrade to Linux Linux 11165fe2c5ea0516debe486d91df67abbe36905e, 718f6a56b40875f19e6915799044a02df9abfd52, 936641af564c3d92721704b781e36aaf223efdd2 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

In the Linux kernel, the following vulnerability has been resolved: ALSA: seq: midi: Serialize output teardown with event_input event_process_midi() borrows msynth->output_rfile.output and then passes the substream to dump_midi() and snd_rawmidi_kernel_write() without synchronizing with the output open/close transition. midisynth_use() also publishes output_rfile before snd_rawmidi_output_params() has finished. The last midisynth_unuse() can therefore release the same rawmidi file and free substream->runtime before snd_rawmidi_kernel_write1() takes its runtime buffer reference. That leaves the event_input path using a stale substream or runtime and can end in a NULL-deref or use-after-free. Fix this with two pieces of synchronization. Keep a short IRQ-safe spinlock only for publishing or clearing output_rfile and for pairing the output snapshot with an snd_use_lock_t reference. Once event_process_midi() has taken that in-flight reference, it drops the spinlock before calling snd_seq_dump_var_event(), dump_midi(), or snd_rawmidi_kernel_write(). midisynth_unuse() now detaches the visible rawmidi file under the same spinlock, waits for the in-flight writers to drain, and only then drains and releases the saved file. midisynth_use() likewise opens into a local snd_rawmidi_file and publishes it only after snd_rawmidi_output_params() succeeds. The buggy scenario involves two paths, with each column showing the order within that path: event_input path: last unuse path: 1. event_process_midi() snapshots 1. midisynth_unuse() starts output_rfile.output. tearing down output_rfile. 2. dump_midi() reaches 2. snd_rawmidi_kernel_release() snd_rawmidi_kernel_write() closes the output file. before runtime is pinned. 3. close_substream() frees 3. The callback keeps using substream->runtime. the borrowed substream. Validation reproduced this kernel report: KASAN null-ptr-deref in snd_rawmidi_kernel_write1+0x56/0x360 RIP: 0033:0x7fde7dd0837f RIP: 0010:snd_rawmidi_kernel_write1+0x56/0x360

HighCVSS 7.8 · v3.1—No exploit Fix available
Published
Aug 15, 2026
Updated
Oct 16, 2026
EPSS
0.1% · 6th percentile
CWE
—

Report tools

JSON

Action score

31

Monitor

Low priority for now.

CVSS
31 / 40 · 7.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · Linux
7.8
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

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Follow CVE-2026-74387

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 2.6.12affected
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before f5d470b808bc01f70978e22e595c6f7768313406affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 936641af564c3d92721704b781e36aaf223efdd2affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 718f6a56b40875f19e6915799044a02df9abfd52affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 11165fe2c5ea0516debe486d91df67abbe36905eaffected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before d6fd2afb137f52bf00c5210cc44d08ed54dcffb4affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before ef7607ab1c8adc6258fb1b27d08e26aecdc18a58affected · git
    • before 2.6.12not affected · semver
    • 6.1.178 and later · up to and including 6.1.*not affected · semver
    • 6.6.145 and later · up to and including 6.6.*not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.180-16.1.180-1
Debian:13linuxbefore 6.12.100-16.12.100-1
Debian:14linuxbefore 7.1.5-17.1.5-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
    40Plan
  • CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
    40Plan
  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-74385Aug 15, 2026 · nvmet-tcp: check return value of nvmet_tcp_set_queue_sock
    30Monitor
  • ← EarlierCVE-2026-74386Aug 15, 2026 · nvmet-tcp: fix page fragment cache leak in error path
    0Monitor
  • Later →CVE-2026-74388Aug 15, 2026 · ALSA: seq: oss: Fix UAF at handling events with embedded SysEx data
    31Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux11165fe2c5ea0516debe486d91df67abbe36905eVendor (CNA)
Linux Linux718f6a56b40875f19e6915799044a02df9abfd52Vendor (CNA)
Linux Linux936641af564c3d92721704b781e36aaf223efdd2Vendor (CNA)
Linux Linuxd6fd2afb137f52bf00c5210cc44d08ed54dcffb4Vendor (CNA)
Linux Linuxef7607ab1c8adc6258fb1b27d08e26aecdc18a58Vendor (CNA)
Linux Linuxf5d470b808bc01f70978e22e595c6f7768313406Vendor (CNA)
debian:linux6.1.180-1 · Debian:12Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

—

CVSS vector

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

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. SSVC exploitation— → none
  2. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (5 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records