VulnerabilityPublished 18 Oct 2026

CVE-2026-98737: Linux kernel · Bluetooth: hci_sync: Fix inquiry cache use-after-free

Source GCVE Database

Authoritative record:CVE-2026-98737

Not known to be exploited · fixed in ddc9edb244cc8b5266595e8fc220e7813f2b603a : update Linux kernel when convenient.

Data as of 26 Oct 2026, 13:47 UTC

Severity

Medium

Rated by Threat Radar · CVSS not yet scored by NVD

EPSS: 0.2% chance of exploitation in 30 days – higher than 9% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in ddc9edb244cc8b5266595e8fc220e7813f2b603a, a642f498f0b08f2aa9f4a69468db92f57a72349d, 333257e6e4a7bcaaea82fd357121d0f1e6b76c7b +2

Exploitation evidence

Disclosed: evidence found.
CVE published 18 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

ghsa-g43c-xvh2-vxh2

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ cf75ad8b41d2aa06f98f365d42a3ae8b059daddd, < ddc9edb244cc8b5266595e8fc220e7813f2b603a	Fixed in ddc9edb244cc8b5266595e8fc220e7813f2b603a
LinuxLinux	Affected ≥ cf75ad8b41d2aa06f98f365d42a3ae8b059daddd, < a642f498f0b08f2aa9f4a69468db92f57a72349d	Fixed in a642f498f0b08f2aa9f4a69468db92f57a72349d
LinuxLinux	Affected ≥ cf75ad8b41d2aa06f98f365d42a3ae8b059daddd, < 333257e6e4a7bcaaea82fd357121d0f1e6b76c7b	Fixed in 333257e6e4a7bcaaea82fd357121d0f1e6b76c7b
LinuxLinux	Affected ≥ cf75ad8b41d2aa06f98f365d42a3ae8b059daddd, < 52edf1c0e59dea37b8368c4a2559dca96b2fdfea	Fixed in 52edf1c0e59dea37b8368c4a2559dca96b2fdfea
LinuxLinux	Affected ≥ cf75ad8b41d2aa06f98f365d42a3ae8b059daddd, < 8ed67535fdff40ca652bcd4ac7da68d11d01bd34	Fixed in 8ed67535fdff40ca652bcd4ac7da68d11d01bd34
LinuxLinux	Affected =5.17	Fixed in–

AI-suggested

A fix has been implemented in the Linux kernel to address this issue by correcting locking behavior and memory handling in the Bluetooth inquiry cache code. Users should apply the official kernel updates containing this fix when available. Patch status is not explicitly confirmed in the provided data; check the vendor advisory for current remediation guidance.

Description

A use-after-free vulnerability in the Linux kernel's Bluetooth hci_sync component was resolved. The issue arises from improper locking during inquiry cache lookups and updates, leading to potential access of freed memory. The fix involves holding the appropriate lock across lookups and copying remote addresses before unlocking to prevent stale pointer usage.

Impact

This vulnerability could lead to use-after-free memory access in the Bluetooth subsystem of the Linux kernel, potentially causing system instability or crashes. No information about exploitation in the wild or privilege escalation is provided.

Summary

The Linux kernel Bluetooth subsystem had a use-after-free vulnerability in the hci_sync code related to inquiry cache handling. The sync command worker held hdev->req_lock, but inquiry cache updates and flushes used hdev->lock. Functions hci_acl_create_conn_sync() and hci_stop_discovery_sync() accessed inquiry cache entries without holding hdev->lock, allowing a concurrent HCIINQUIRY ioctl to flush the cache and free entries while they were still being accessed. This caused use-after-free bugs detected by KASAN. The fix ensures hdev->lock is held during lookups and reads, copies remote addresses before unlocking, and releases the lock before sending synchronous HCI commands to avoid lock contention in completion handlers.

References

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