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NVD / CVE Program· CNA Linux

CVE-2025-21969: Bluetooth: L2CAP: Fix slab-use-after-free Read in l2cap_send_cmd

Noroxi assessment

Priority: Monitor (action score 31/100)

  • 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: 0.23% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 5.18, 7790a79c6fce8d5d552bc64f5c82819f719e4f28, b4f82f9ed43aefa79bec2504ae8c29be0c0f5d1d; azl3 kernel 6.6.82.1-1 on Azure Linux 3.0 6.6.85.1-2; azl3 kernel 6.6.85.1-2 on Azure Linux 3.0 6.6.85.1-2.

Low priority for now. Upgrade to Linux Linux 5.18, 7790a79c6fce8d5d552bc64f5c82819f719e4f28, b4f82f9ed43aefa79bec2504ae8c29be0c0f5d1d; azl3 kernel 6.6.82.1-1 on Azure Linux 3.0 6.6.85.1-2; azl3 kernel 6.6.85.1-2 on Azure Linux 3.0 6.6.85.1-2 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: L2CAP: Fix slab-use-after-free Read in l2cap_send_cmd After the hci sync command releases l2cap_conn, the hci receive data work queue references the released l2cap_conn when sending to the upper layer. Add hci dev lock to the hci receive data work queue to synchronize the two. [1] BUG: KASAN: slab-use-after-free in l2cap_send_cmd+0x187/0x8d0 net/bluetooth/l2cap_core.c:954 Read of size 8 at addr ffff8880271a4000 by task kworker/u9:2/5837 CPU: 0 UID: 0 PID: 5837 Comm: kworker/u9:2 Not tainted 6.13.0-rc5-syzkaller-00163-gab75170520d4 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 Workqueue: hci1 hci_rx_work Call Trace: <TASK> __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0x169/0x550 mm/kasan/report.c:489 kasan_report+0x143/0x180 mm/kasan/report.c:602 l2cap_build_cmd net/bluetooth/l2cap_core.c:2964 [inline] l2cap_send_cmd+0x187/0x8d0 net/bluetooth/l2cap_core.c:954 l2cap_sig_send_rej net/bluetooth/l2cap_core.c:5502 [inline] l2cap_sig_channel net/bluetooth/l2cap_core.c:5538 [inline] l2cap_recv_frame+0x221f/0x10db0 net/bluetooth/l2cap_core.c:6817 hci_acldata_packet net/bluetooth/hci_core.c:3797 [inline] hci_rx_work+0x508/0xdb0 net/bluetooth/hci_core.c:4040 process_one_work kernel/workqueue.c:3229 [inline] process_scheduled_works+0xa66/0x1840 kernel/workqueue.c:3310 worker_thread+0x870/0xd30 kernel/workqueue.c:3391 kthread+0x2f0/0x390 kernel/kthread.c:389 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 </TASK> Allocated by task 5837: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x3f/0x80 mm/kasan/common.c:68 poison_kmalloc_redzone mm/kasan/common.c:377 [inline] __kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:394 kasan_kmalloc include/linux/kasan.h:260 [inline] __kmalloc_cache_noprof+0x243/0x390 mm/slub.c:4329 kmalloc_noprof include/linux/slab.h:901 [inline] kzalloc_noprof include/linux/slab.h:1037 [inline] l2cap_conn_add+0xa9/0x8e0 net/bluetooth/l2cap_core.c:6860 l2cap_connect_cfm+0x115/0x1090 net/bluetooth/l2cap_core.c:7239 hci_connect_cfm include/net/bluetooth/hci_core.h:2057 [inline] hci_remote_features_evt+0x68e/0xac0 net/bluetooth/hci_event.c:3726 hci_event_func net/bluetooth/hci_event.c:7473 [inline] hci_event_packet+0xac2/0x1540 net/bluetooth/hci_event.c:7525 hci_rx_work+0x3f3/0xdb0 net/bluetooth/hci_core.c:4035 process_one_work kernel/workqueue.c:3229 [inline] process_scheduled_works+0xa66/0x1840 kernel/workqueue.c:3310 worker_thread+0x870/0xd30 kernel/workqueue.c:3391 kthread+0x2f0/0x390 kernel/kthread.c:389 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 Freed by task 54: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x3f/0x80 mm/kasan/common.c:68 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:582 poison_slab_object mm/kasan/common.c:247 [inline] __kasan_slab_free+0x59/0x70 mm/kasan/common.c:264 kasan_slab_free include/linux/kasan.h:233 [inline] slab_free_hook mm/slub.c:2353 [inline] slab_free mm/slub.c:4613 [inline] kfree+0x196/0x430 mm/slub.c:4761 l2cap_connect_cfm+0xcc/0x1090 net/bluetooth/l2cap_core.c:7235 hci_connect_cfm include/net/bluetooth/hci_core.h:2057 [inline] hci_conn_failed+0x287/0x400 net/bluetooth/hci_conn.c:1266 hci_abort_conn_sync+0x56c/0x11f0 net/bluetooth/hci_sync.c:5603 hci_cmd_sync_work+0x22b/0x400 net/bluetooth/hci_sync.c:332 process_one_work kernel/workqueue.c:3229 [inline] process_scheduled_works+0xa66/0x1840 kernel/workqueue.c:3310 worker_thread+0x870/0xd30 kernel/workqueue.c:3391 kthread+0x2f0/0x390 kernel/kthread.c:389 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entr ---truncated---

HighCVSS 7.8 · v3.1—No exploit Fix available
Published
Apr 1, 2025
Updated
Aug 5, 2026
EPSS
0.2% · 13th percentile

Report tools

JSON

Action score

31

Monitor

Low priority for now.

CVSS
31 / 40 · 7.8 / 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
7.8
CNA · Linux
8.8
1.0 point gap

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

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2025-21969

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  • when exploit code appears or is weaponized
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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.

VendorProduct
linuxlinux kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernelbefore 6.6.84
  • linux linux kernel6.7 and later · before 6.12.20
  • linux linux kernel6.13 and later · before 6.13.8
  • linux linux kernel6.14

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

    • 995c917d6818b39308ac6baf3f6573cb0486a238, 5.18affected
    • 9b3628d79b46f06157affc56fdb218fdd4988321 and later · before c96cce853542b3b13da3738f35ef1be8cfcc9d1daffected · git
    • 9b3628d79b46f06157affc56fdb218fdd4988321 and later · before f8094625a591eeb0b75b1bd9e713fac1d93f5ca9affected · git
    • 9b3628d79b46f06157affc56fdb218fdd4988321 and later · before 7790a79c6fce8d5d552bc64f5c82819f719e4f28affected · git
    • 9b3628d79b46f06157affc56fdb218fdd4988321 and later · before b4f82f9ed43aefa79bec2504ae8c29be0c0f5d1daffected · git
    • 5.17.14 and later · before 5.18affected · semver
    • before 5.18not affected · semver
    • 6.6.84 and later · up to and including 6.6.*not affected · semver
    • 6.12.20 and later · up to and including 6.12.*not affected · semver
    • 6.13.8 and later · up to and including 6.13.*not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
AlmaLinux:9kernelbefore 5.14.0-570.22.1.el9_65.14.0-570.22.1.el9_6
AlmaLinux:9kernel-64kbefore 5.14.0-570.22.1.el9_65.14.0-570.22.1.el9_6
AlmaLinux:9kernel-64k-corebefore 5.14.0-570.22.1.el9_65.14.0-570.22.1.el9_6
AlmaLinux:9kernel-64k-debugbefore 5.14.0-570.22.1.el9_65.14.0-570.22.1.el9_6
AlmaLinux:9kernel-64k-debug-corebefore 5.14.0-570.22.1.el9_65.14.0-570.22.1.el9_6
AlmaLinux:9kernel-64k-debug-develbefore 5.14.0-570.22.1.el9_65.14.0-570.22.1.el9_6
AlmaLinux:9kernel-64k-debug-devel-matchedbefore 5.14.0-570.22.1.el9_65.14.0-570.22.1.el9_6
AlmaLinux:9kernel-64k-debug-modulesbefore 5.14.0-570.22.1.el9_65.14.0-570.22.1.el9_6
AlmaLinux:9kernel-64k-debug-modules-corebefore 5.14.0-570.22.1.el9_65.14.0-570.22.1.el9_6
AlmaLinux:9kernel-64k-debug-modules-extrabefore 5.14.0-570.22.1.el9_65.14.0-570.22.1.el9_6
AlmaLinux:9kernel-64k-develbefore 5.14.0-570.22.1.el9_65.14.0-570.22.1.el9_6
AlmaLinux:9kernel-64k-devel-matchedbefore 5.14.0-570.22.1.el9_65.14.0-570.22.1.el9_6
AlmaLinux:9kernel-64k-modulesbefore 5.14.0-570.22.1.el9_65.14.0-570.22.1.el9_6
AlmaLinux:9kernel-64k-modules-corebefore 5.14.0-570.22.1.el9_65.14.0-570.22.1.el9_6
AlmaLinux:9kernel-64k-modules-extrabefore 5.14.0-570.22.1.el9_65.14.0-570.22.1.el9_6
AlmaLinux:9kernel-abi-stablelistsbefore 5.14.0-570.22.1.el9_65.14.0-570.22.1.el9_6
AlmaLinux:9kernel-corebefore 5.14.0-570.22.1.el9_65.14.0-570.22.1.el9_6
AlmaLinux:9kernel-cross-headersbefore 5.14.0-570.22.1.el9_65.14.0-570.22.1.el9_6
AlmaLinux:9kernel-debugbefore 5.14.0-570.22.1.el9_65.14.0-570.22.1.el9_6
AlmaLinux:9kernel-debug-corebefore 5.14.0-570.22.1.el9_65.14.0-570.22.1.el9_6
AlmaLinux:9kernel-debug-develbefore 5.14.0-570.22.1.el9_65.14.0-570.22.1.el9_6
AlmaLinux:9kernel-debug-devel-matchedbefore 5.14.0-570.22.1.el9_65.14.0-570.22.1.el9_6
AlmaLinux:9kernel-debug-modulesbefore 5.14.0-570.22.1.el9_65.14.0-570.22.1.el9_6
AlmaLinux:9kernel-debug-modules-corebefore 5.14.0-570.22.1.el9_65.14.0-570.22.1.el9_6

+96

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
    90Now
  • CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now

Published before and after this one in the same product

  • ← EarlierCVE-2025-21967Apr 1, 2025 · ksmbd: fix use-after-free in ksmbd_free_work_struct
    31Monitor
  • ← EarlierCVE-2025-21968Apr 1, 2025 · drm/amd/display: Fix slab-use-after-free on hdcp_work
    31Monitor
  • Later →CVE-2025-21973Apr 1, 2025 · eth: bnxt: fix kernel panic in the bnxt_get_queue_stats{rx | tx}
    28Monitor

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 Linux5.18Vendor (CNA)
Linux Linux7790a79c6fce8d5d552bc64f5c82819f719e4f28Vendor (CNA)
Linux Linuxb4f82f9ed43aefa79bec2504ae8c29be0c0f5d1dVendor (CNA)
Linux Linuxc96cce853542b3b13da3738f35ef1be8cfcc9d1dVendor (CNA)
Linux Linuxf8094625a591eeb0b75b1bd9e713fac1d93f5ca9Vendor (CNA)
azl3 kernel 6.6.82.1-1 on Azure Linux 3.06.6.85.1-2 · CBL-Mariner ReleasesMicrosoft (MSRC)
azl3 kernel 6.6.85.1-2 on Azure Linux 3.06.6.85.1-2 · CBL-Mariner ReleasesMicrosoft (MSRC)
almalinux:kernel5.14.0-570.22.1.el9_6 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k5.14.0-570.22.1.el9_6 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-core5.14.0-570.22.1.el9_6 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug5.14.0-570.22.1.el9_6 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-core5.14.0-570.22.1.el9_6 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-devel5.14.0-570.22.1.el9_6 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-devel-matched5.14.0-570.22.1.el9_6 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-modules5.14.0-570.22.1.el9_6 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-modules-core5.14.0-570.22.1.el9_6 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-modules-extra5.14.0-570.22.1.el9_6 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-devel5.14.0-570.22.1.el9_6 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-devel-matched5.14.0-570.22.1.el9_6 · AlmaLinux:9Package registry (OSV)
debian:linux6.12.20-1 · Debian:13Package registry (OSV)
red hat:kernel-64k-debug-debuginfo0:6.12.0-55.17.1.el10_0 · Red Hat:enterprise_linux:10.0Package registry (OSV)
red hat:kernel-64k-debug-devel0:6.12.0-55.17.1.el10_0 · Red Hat:enterprise_linux:10.0Package registry (OSV)
red hat:kernel-64k-debug-devel-matched0:6.12.0-55.17.1.el10_0 · Red Hat:enterprise_linux:10.0Package registry (OSV)
red hat:kernel-64k-debuginfo0:6.12.0-55.17.1.el10_0 · Red Hat:enterprise_linux:10.0Package registry (OSV)
red hat:kernel-64k-devel0:6.12.0-55.17.1.el10_0 · Red Hat:enterprise_linux:10.0Package registry (OSV)
red hat:kernel-64k-devel-matched0:6.12.0-55.17.1.el10_0 · Red Hat:enterprise_linux:10.0Package registry (OSV)
red hat:kernel-debug-debuginfo0:6.12.0-55.17.1.el10_0 · Red Hat:enterprise_linux:10.0Package registry (OSV)
red hat:kernel-debug-devel0:6.12.0-55.17.1.el10_0 · Red Hat:enterprise_linux:10.0Package registry (OSV)
red hat:kernel-debug-devel-matched0:6.12.0-55.17.1.el10_0 · Red Hat:enterprise_linux:10.0Package registry (OSV)
red hat:kernel-debuginfo0:6.12.0-55.17.1.el10_0 · Red Hat:enterprise_linux:10.0Package registry (OSV)

+3

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

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

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).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • 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
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-416 · Use After Free

CVSS vector

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

nvd-primary

Root cause

After a memory region is freed, another reference pointing to it is still used. By then, the same region may have been allocated for different data.

The bug in code

The whole CWE-416 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

c
free(dev->buf);/* ... another thread is still running ... */process(dev->buf);

Fixed

c
lock(&dev->lock);free(dev->buf);dev->buf = NULL;unlock(&dev->lock);

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✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (3 more)

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

All records