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NVD / CVE Program· CNA Linux

CVE-2026-97975: Bluetooth: hci_sysfs: Fix NULL pointer dereference in device_del()

Noroxi assessment

Priority: Monitor (action score 0/100)

  • 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: 0.16% (FIRST EPSS).
  • Fixed version: Linux Linux 5.11, 5.16, 5.5; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 6.6.159.1-1.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 5.11, 5.16, 5.5; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 6.6.159.1-1 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: hci_sysfs: Fix NULL pointer dereference in device_del() A NULL pointer dereference in klist_put() occurs when a child device (such as a BNEP network device in bnep_session) is concurrently being unregistered while hci_conn_del_sysfs() reparents child devices. This is caused by a race condition between hci_conn_del_sysfs() and concurrent child device unregistration (e.g. bnep_session calling unregister_netdev()). During device unregistration, device_del() snapshots a non-NULL parent pointer. Concurrently, hci_conn_del_sysfs() finds the child device using device_find_any_child() and calls device_move() to reparent it to NULL, which removes the node from its parent's klist and clears knode_parent. Subsequently, device_del() calls klist_del(&dev->p->knode_parent) using the stale parent snapshot, causing klist_put() to dereference knode_klist(n)->put on an already removed node, resulting in a NULL pointer dereference. This race was introduced by commit 27aabf27fd01 ("Bluetooth: fix use-after-free in device_for_each_child()"), which replaced device_find_child(..., __match_tty) with device_find_any_child() in hci_conn_del_sysfs(). That change was intended to avoid a use-after-free where conn->dev outlived its parent hdev->dev when child devices held references to conn->dev, because conn->dev only held a reference to hdev->dev while registered in sysfs. Fix the issue properly by taking an explicit reference to the parent device with get_device(&hdev->dev) in hci_conn_init_sysfs() and dropping it with put_device(parent) in bt_link_release() when the conn device is freed. This ensures that hdev->dev remains valid for the entire lifecycle of conn->dev, resolving the underlying use-after-free. With the parent reference held properly, restore the __match_tty filter in hci_conn_del_sysfs() so that device_move() is only invoked on persistent RFCOMM TTY devices as originally intended, eliminating the race condition with unregistering network devices.

—No exploit Fix available
Published
Sep 25, 2026
Updated
Oct 21, 2026
EPSS
0.1% · 6th percentile
CWE
—

Report tools

JSON

Action score

0

Monitor

Low priority for now.

CVSS
0 / 40 · —
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

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Noroxi analysis

What does it mean in your environment?

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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

    • 6894717a1ea363c5a27010ba604f957c309d282d, fb91ce37dc9a37ea23cf32b6d7b667004e93d4c5, a9584c897d1cba6265c78010bbb45ca5722c88bc, 0f67ca2a80acf8b207240405b7f72d660665d3df, 91e2a2e4d1336333804cd31162984f01ad8cc70f, 6.13affected
    • de5a44f351ca7efd9add9851b218f5353e2224b7 and later · before 55b76500546e5f2e7fdd7ae7283530b620de6e61affected · git
    • 7b277bd569bb6a2777f0014f84b4344f444fd49d and later · before 66cc55b69928b742d24b4c5b66d195ae96900e48affected · git
    • 27aabf27fd014ae037cc179c61b0bee7cff55b3d and later · before eeabdb25c3209569367e99a85ca9a503b64a646daffected · git
    • 27aabf27fd014ae037cc179c61b0bee7cff55b3d and later · before 9e9ece97b8e716890793de261574b8efef7d8702affected · git
    • 27aabf27fd014ae037cc179c61b0bee7cff55b3d and later · before 9b851b09b392da68bd715601f10a5adb2d8d19b8affected · git
    • 6.6.64 and later · before 6.6.160affected · semver
    • 6.12.2 and later · before 6.12.114affected · semver
    • 5.4.297 and later · before 5.5affected · semver
    • 5.10.231 and later · before 5.11affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxfrom 0—
Debian:14linuxbefore 7.2.7-17.2.7-1

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-2026-97973Sep 25, 2026 · net: macb: destroy the phylink instance on the probe error path
    0Monitor
  • ← EarlierCVE-2026-97974Sep 25, 2026 · ipv6: null-check fib6_node before accessing in __ip6_del_rt_siblings()
    0Monitor
  • Later →CVE-2026-97976Sep 25, 2026 · Bluetooth: btintel_pcie: validate packet_len before skb_put_data
    0Monitor

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 Linux5.11Vendor (CNA)
Linux Linux5.16Vendor (CNA)
Linux Linux5.5Vendor (CNA)
Linux Linux55b76500546e5f2e7fdd7ae7283530b620de6e61Vendor (CNA)
Linux Linux6.12Vendor (CNA)
Linux Linux6.12.114Vendor (CNA)
Linux Linux6.2Vendor (CNA)
Linux Linux6.6.160Vendor (CNA)
Linux Linux66cc55b69928b742d24b4c5b66d195ae96900e48Vendor (CNA)
Linux Linux9b851b09b392da68bd715601f10a5adb2d8d19b8Vendor (CNA)
Linux Linux9e9ece97b8e716890793de261574b8efef7d8702Vendor (CNA)
Linux Linuxeeabdb25c3209569367e99a85ca9a503b64a646dVendor (CNA)
azl3 kernel 6.6.157.1-1 on Azure Linux 3.06.6.159.1-1 · Release NotesMicrosoft (MSRC)
debian:linux7.2.7-1 · 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).

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

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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).

National notice (Türkiye Cybersecurity Directorate / USOM)

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

All national notices →

Technical details

No CVSS vector for this record, so attack conditions can't be derived.

Weakness class (CWE)

—

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. Fix✗ → ✓

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References

Show all references (4 more)

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

All records