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NVD / CVE Program· CNA Linux

CVE-2026-74534: Bluetooth: ISO: fix refcounting of iso_conn

HighCVSS 8.8 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 35/100)

  • 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: 0.24% (FIRST EPSS).
  • Someone on the same network segment can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 3b921533e8aa95b77aadcf31737595578e735f3c, 42c8bd6ac81e21200bb90f1eaf43d19352eec6d7, 6.12.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 3b921533e8aa95b77aadcf31737595578e735f3c, 42c8bd6ac81e21200bb90f1eaf43d19352eec6d7, 6.12 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: Bluetooth: ISO: fix refcounting of iso_conn iso_conn_del() and iso_chan_del() have a race that results to double-put of iso_conn: [Task hdev->workqueue] [Task 2] iso_conn_del iso_chan_del iso_conn_hold_unless_zero iso_conn_lock iso_conn_lock conn->sk = NULL iso_conn_unlock sk = iso_sock_hold(conn) <---------´ if (!sk) iso_conn_put iso_conn_put iso_conn_put /* UAF */ The extra put for !sk in iso_conn_del() is currently required since failing iso_chan_add() may leave iso_conn not associated with any sk. Fix by having iso_pi(sk)->conn own refcount when non-NULL, so iso_conn_del does not need to put it. Adjust the iso_conn_add() refcounting so that conn is put if it does not get associated with an sk.

Published
Aug 15, 2026
Updated
Oct 23, 2026
EPSS
0.2% · 15th percentile
CWE
—

Report tools

JSON

Action score

35

Monitor

Low priority for now.

CVSS
35 / 40 · 8.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.2%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · Linux
8.8
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.

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  • 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-2026-74534

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  • when exploit code appears or is weaponized
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  • 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

    • f53e7489273dc2bb307bf50f319b3762d45534f0, 6.13affected
    • a58d0f5dac322e16cc75334d000666512341bde5 and later · before 42c8bd6ac81e21200bb90f1eaf43d19352eec6d7affected · git
    • dc26097bdb864a0d5955b9a25e43376ffc1af99b and later · before 3b921533e8aa95b77aadcf31737595578e735f3caffected · git
    • dc26097bdb864a0d5955b9a25e43376ffc1af99b and later · before 8208b4939afb0a1977fffe902c3ca42fe0f3baaaaffected · git
    • dc26097bdb864a0d5955b9a25e43376ffc1af99b and later · before fdfde532ab1caa165fcd8985001157ac8b4db365affected · git
    • 6.12.2 and later · before 6.12.113affected · semver
    • 6.11.11 and later · before 6.12affected · semver
    • before 6.13not affected · semver
    • 6.12.113 and later · up to and including 6.12.*not affected · semver
    • 6.18.44 and later · up to and including 6.18.*not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:13linuxbefore 6.12.113-16.12.113-1
Debian:14linuxbefore 7.1.8-17.1.8-1

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-2026-74531Aug 15, 2026 · Bluetooth: hci_conn: hold conn reference in abort_conn_sync()
    35Monitor
  • ← EarlierCVE-2026-74533Aug 15, 2026 · Bluetooth: ISO: fix race of kfree vs kref_get_unless_zero
    35Monitor
  • Later →CVE-2026-74535Aug 15, 2026 · Bluetooth: ISO: avoid deadlocks in iso_sock_timeout
    35Monitor

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 Linux3b921533e8aa95b77aadcf31737595578e735f3cVendor (CNA)
Linux Linux42c8bd6ac81e21200bb90f1eaf43d19352eec6d7Vendor (CNA)
Linux Linux6.12Vendor (CNA)
Linux Linux6.12.113Vendor (CNA)
Linux Linux8208b4939afb0a1977fffe902c3ca42fe0f3baaaVendor (CNA)
Linux Linuxfdfde532ab1caa165fcd8985001157ac8b4db365Vendor (CNA)
debian:linux6.12.113-1 · Debian:13Package registry (OSV)
debian:linux7.1.8-1 · Debian:14Package 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).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Not on record for this CVE: patch commit or PR link · researcher credit · variant or chain candidate · public bounty program.

Technical details

Attack conditions

  • Someone on the same network segment can trigger it.
  • No account or password is required.
  • 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
Adjacent
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

—

CVSS vector

CVSS:3.1/AV:A/AC:L/PR:N/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.

References

Show all references (3 more)

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

All records