CyberSecBulletin
CVE-2025-38593NVD status: Modified

Linux: Double Free

Published Updated By the CyberSecBulletin desk

CVE-2025-38593 is a high-severity double free vulnerability in Linux, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions 86f3dcd1f331cfd4fd7ec88906955134ec51afbe, 7ce9bb0b95fc280e9212b8922590c492ca1d9c39, 16852eccbdfaf41a666705e3f8be55cf2864c5ca as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.19% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to 86f3dcd1f331cfd4fd7ec88906955134ec51afbe or 7ce9bb0b95fc280e9212b8922590c492ca1d9c39 or 16852eccbdfaf41a666705e3f8be55cf2864c5ca or a351ff6b8ecca4229afaa0d98042bead8de64799, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 6.6.117 or 6.12.42 or 6.15.10 or 6.16.1, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinuxad383c2c65a5baf16e334cd40a013cc302176891 up to, but not including, 86f3dcd1f331cfd4fd7ec88906955134ec51afbe; ad383c2c65a5baf16e334cd40a013cc302176891 up to, but not including, 7ce9bb0b95fc280e9212b8922590c492ca1d9c39; ad383c2c65a5baf16e334cd40a013cc302176891 up to, but not including, 16852eccbdfaf41a666705e3f8be55cf2864c5ca; ad383c2c65a5baf16e334cd40a013cc302176891 up to, but not including, a351ff6b8ecca4229afaa0d98042bead8de64799; ad383c2c65a5baf16e334cd40a013cc302176891 up to, but not including, f8069f34c4c976786ded97498012225af87435d7; ad383c2c65a5baf16e334cd40a013cc302176891 up to, but not including, 2935e556850e9c94d7a00adf14d3cd7fe406ac03; 5.1786f3dcd1f331cfd4fd7ec88906955134ec51afbe, 7ce9bb0b95fc280e9212b8922590c492ca1d9c39, 16852eccbdfaf41a666705e3f8be55cf2864c5ca, a351ff6b8ecca4229afaa0d98042bead8de64799, f8069f34c4c976786ded97498012225af87435d7, 2935e556850e9c94d7a00adf14d3cd7fe406ac03
LinuxLinux Kernel5.17 up to, but not including, 6.6.117; 6.7 up to, but not including, 6.12.42; 6.13 up to, but not including, 6.15.10; 6.16 up to, but not including, 6.16.16.6.117, 6.12.42, 6.15.10, 6.16.1

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

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

Scoring systemScoreSeverityScored by
CVSS 3.17.8HighCNA
CVSS 3.17.8HighNVD

Official description

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 ]---

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Double Free

The product calls free() twice on the same memory address.

How developers prevent this class of flaw

  • Choose a language that provides automatic memory management.
  • Ensure that each allocation is freed only once. After freeing a chunk, set the pointer to NULL to ensure the pointer cannot be freed again. In complicated error conditions, be sure that clean-up routines respect the state of allocation properly. If the language is object oriented, ensure that object destructors delete each chunk of memory only once.
  • Use a static analysis tool to find double free instances.

More Double Free vulnerabilities (CWE-415)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Double Free vulnerabilities

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