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CVE Record

CVE-2025-38593: Bluetooth: hci_sync: fix double free in 'hci_discovery_filter_clear()'

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: hci_sync: fix double free in 'hci_discovery_filter_clear()' Function 'hci_discovery_filter_clear()' frees 'uuids' array and then sets it to NULL. There is a tiny chance of the following race: 'hci_cmd_sync_work()' 'update_passive_scan_sync()' 'hci_update_passive_scan_sync()' 'hci_discovery_filter_clear()' kfree(uuids); <-------------------------preempted--------------------------------> 'start_service_discovery()' 'hci_discovery_filter_clear()' kfree(uuids); // DOUBLE FREE <-------------------------preempted--------------------------------> uuids = NULL; To fix it let's add locking around 'kfree()' call and NULL pointer assignment. Otherwise the following backtrace fires: [ ] ------------[ cut here ]------------ [ ] kernel BUG at mm/slub.c:547! [ ] Internal error: Oops - BUG: 00000000f2000800 [#1] PREEMPT SMP [ ] CPU: 3 UID: 0 PID: 246 Comm: bluetoothd Tainted: G O 6.12.19-kernel #1 [ ] Tainted: [O]=OOT_MODULE [ ] pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) [ ] pc : __slab_free+0xf8/0x348 [ ] lr : __slab_free+0x48/0x348 ... [ ] Call trace: [ ] __slab_free+0xf8/0x348 [ ] kfree+0x164/0x27c [ ] start_service_discovery+0x1d0/0x2c0 [ ] hci_sock_sendmsg+0x518/0x924 [ ] __sock_sendmsg+0x54/0x60 [ ] sock_write_iter+0x98/0xf8 [ ] do_iter_readv_writev+0xe4/0x1c8 [ ] vfs_writev+0x128/0x2b0 [ ] do_writev+0xfc/0x118 [ ] __arm64_sys_writev+0x20/0x2c [ ] invoke_syscall+0x68/0xf0 [ ] el0_svc_common.constprop.0+0x40/0xe0 [ ] do_el0_svc+0x1c/0x28 [ ] el0_svc+0x30/0xd0 [ ] el0t_64_sync_handler+0x100/0x12c [ ] el0t_64_sync+0x194/0x198 [ ] Code: 8b0002e6 eb17031f 54fffbe1 d503201f (d4210000) [ ] ---[ end trace 0000000000000000 ]---

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A race condition in the Linux Bluetooth subsystem can free the same memory twice, potentially causing a kernel crash. The supplied CVSS assessment also indicates possible confidentiality and integrity impact. Exploitation requires local, low-privileged access; this is not described as a remotely exploitable Bluetooth attack.

Executive priority

Prioritize remediation as high for Bluetooth-enabled systems accessible to untrusted local users. Treat internet-facing status alone as insufficient evidence of exposure because the rated attack vector is local. Use normal accelerated kernel patching, with greater urgency for shared endpoints, kiosks, and operational systems where a kernel crash would materially disrupt service.

Technical view

Concurrent passive-scan and service-discovery paths can enter hci_discovery_filter_clear() before the freed UUID pointer is set to NULL. Both paths may call kfree() on the same allocation, producing a double free and kernel Oops. The referenced stable-kernel changes add locking around the free and NULL assignment.

Likely exposure

Exposure is most likely on affected Linux kernels where Bluetooth is enabled and service-discovery or passive-scan operations occur. The bundle lists versions from 5.17 through 6.17, but its flattened version data does not clearly define every affected or fixed interval. Confirm status through the system vendor.

Exploitation context

The supplied CVSS vector rates exploitation as local, low complexity, requiring low privileges and no user interaction. The bundle demonstrates a kernel crash involving bluetoothd but provides no evidence of reliable privilege escalation or data compromise. It is not in CISA KEV, and no active exploitation is cited.

Researcher notes

The race window occurs between kfree(uuids) and uuids = NULL when two Bluetooth control paths interleave. The source provides a crash trace, not a demonstrated security exploit. No CWE is assigned. Exact vulnerable release boundaries and commit-to-branch mappings are unclear in the supplied normalized version list, so vendor package analysis remains necessary.

Mitigation direction

  • Apply a vendor-supported kernel update containing the referenced locking fix.
  • Check distribution advisories for exact affected and fixed package versions.
  • Prioritize Bluetooth-enabled multi-user systems where untrusted local users have access.
  • Restrict unnecessary local access to Bluetooth functionality until patched.

Validation and detection

  • Record the running kernel and distribution package versions.
  • Compare installed packages with the distribution vendor's CVE advisory.
  • Confirm the installed kernel contains the applicable referenced stable commit.
  • Verify Bluetooth exposure and identify systems running bluetoothd.
  • Review kernel logs for Bluetooth-related slab errors, Oops, or crashes.
Prepared
Confidence
high
Sources
8

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

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CVE-2025-38593 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.8 (3.1)
Known Exploited
No
Published

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

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
3Timeline events
0ADP providers
7Source links

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.8CVSS 3.1HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9Linux

Vulnerability scoring details

Base CVSS 3.1 score

7.8High
CVSS 3.1 vector shape for CVE-2025-38593Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxad383c2c65a5baf16e334cd40a013cc302176891, ad383c2c65a5baf16e334cd40a013cc302176891, ad383c2c65a5baf16e334cd40a013cc302176891, ad383c2c65a5baf16e334cd40a013cc302176891, ad383c2c65a5baf16e334cd40a013cc302176891, ad383c2c65a5baf16e334cd40a013cc302176891unaffected
LinuxLinux5.17, 0, 6.1.159, 6.6.117, 6.12.42, 6.15.10, 6.16.1, 6.17affected
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.