Linux Kernel up to 6.17-rc1 ets_class_qlen_notify null pointer dereference

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5.0$0-$5k0.00

Summaryinfo

A vulnerability was found in Linux Kernel up to 6.17-rc1. It has been classified as critical. The affected element is the function ets_class_qlen_notify. This manipulation causes null pointer dereference. This vulnerability is tracked as CVE-2025-38684. No exploit exists. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability has been found in Linux Kernel up to 6.17-rc1 and classified as critical. Affected by this vulnerability is the function ets_class_qlen_notify. The manipulation with an unknown input leads to a null pointer dereference vulnerability. The CWE definition for the vulnerability is CWE-476. A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. As an impact it is known to affect availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: net/sched: ets: use old 'nbands' while purging unused classes Shuang reported sch_ets test-case [1] crashing in ets_class_qlen_notify() after recent changes from Lion [2]. The problem is: in ets_qdisc_change() we purge unused DWRR queues; the value of 'q->nbands' is the new one, and the cleanup should be done with the old one. The problem is here since my first attempts to fix ets_qdisc_change(), but it surfaced again after the recent qdisc len accounting fixes. Fix it purging idle DWRR queues before assigning a new value of 'q->nbands', so that all purge operations find a consistent configuration: - old 'q->nbands' because it's needed by ets_class_find() - old 'q->nstrict' because it's needed by ets_class_is_strict() BUG: kernel NULL pointer dereference, address: 0000000000000000 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: Oops: 0000 [#1] SMP NOPTI CPU: 62 UID: 0 PID: 39457 Comm: tc Kdump: loaded Not tainted 6.12.0-116.el10.x86_64 #1 PREEMPT(voluntary) Hardware name: Dell Inc. PowerEdge R640/06DKY5, BIOS 2.12.2 07/09/2021 RIP: 0010:__list_del_entry_valid_or_report+0x4/0x80 Code: ff 4c 39 c7 0f 84 39 19 8e ff b8 01 00 00 00 c3 cc cc cc cc 66 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa <48> 8b 17 48 8b 4f 08 48 85 d2 0f 84 56 19 8e ff 48 85 c9 0f 84 ab RSP: 0018:ffffba186009f400 EFLAGS: 00010202 RAX: 00000000000000d6 RBX: 0000000000000000 RCX: 0000000000000004 RDX: ffff9f0fa29b69c0 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffffffffc12c2400 R08: 0000000000000008 R09: 0000000000000004 R10: ffffffffffffffff R11: 0000000000000004 R12: 0000000000000000 R13: ffff9f0f8cfe0000 R14: 0000000000100005 R15: 0000000000000000 FS: 00007f2154f37480(0000) GS:ffff9f269c1c0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 00000001530be001 CR4: 00000000007726f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 PKRU: 55555554 Call Trace: <TASK> ets_class_qlen_notify+0x65/0x90 [sch_ets] qdisc_tree_reduce_backlog+0x74/0x110 ets_qdisc_change+0x630/0xa40 [sch_ets] __tc_modify_qdisc.constprop.0+0x216/0x7f0 tc_modify_qdisc+0x7c/0x120 rtnetlink_rcv_msg+0x145/0x3f0 netlink_rcv_skb+0x53/0x100 netlink_unicast+0x245/0x390 netlink_sendmsg+0x21b/0x470 ____sys_sendmsg+0x39d/0x3d0 ___sys_sendmsg+0x9a/0xe0 __sys_sendmsg+0x7a/0xd0 do_syscall_64+0x7d/0x160 entry_SYSCALL_64_after_hwframe+0x76/0x7e RIP: 0033:0x7f2155114084 Code: 89 02 b8 ff ff ff ff eb bb 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 f3 0f 1e fa 80 3d 25 f0 0c 00 00 74 13 b8 2e 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 54 c3 0f 1f 00 48 83 ec 28 89 54 24 1c 48 89 RSP: 002b:00007fff1fd7a988 EFLAGS: 00000202 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 0000560ec063e5e0 RCX: 00007f2155114084 RDX: 0000000000000000 RSI: 00007fff1fd7a9f0 RDI: 0000000000000003 RBP: 00007fff1fd7aa60 R08: 0000000000000010 R09: 000000000000003f R10: 0000560ee9b3a010 R11: 0000000000000202 R12: 00007fff1fd7aae0 R13: 000000006891ccde R14: 0000560ec063e5e0 R15: 00007fff1fd7aad0 </TASK> [1] https://lore.kernel.org/netdev/e08c7f4a6882f260011909a868311c6e9b54f3e4.1639153474.git.dcaratti@redhat.com/ [2] https://lore.kernel.org/netdev/[email protected]/

The advisory is shared at git.kernel.org. This vulnerability is known as CVE-2025-38684 since 04/16/2025. The exploitation appears to be difficult. Technical details are known, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 261576 (Linux Distros Unpatched Vulnerability : CVE-2025-38684), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 5.10.241, 5.15.190, 6.1.149, 6.6.103, 6.12.43, 6.15.11, 6.16.2 or 6.17-rc2 eliminates this vulnerability. Applying the patch bdfddcde86e8b9245d9c0c2efe2b6fe8dcf6bf41/be9692dafdfb36d9c43afd9d4e1d9d9ba8e7b51b/97ec167cd2e8a81a2d87331a2ed92daf007542c8/84a24fb446ee07b22b64aae6f0e3f4a38266310a/5b3b346bc4c2aa2c428735438a11989d251f32f1/d69f4a258cd91b3bcef7089eb0401005aae2aed5/970c1c731c4ede46d05f5b0355724d1e400cfbca/87c6efc5ce9c126ae4a781bc04504b83780e3650 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (261576) and CERT Bund (WID-SEC-2025-1976). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Affected

  • Debian Linux
  • Amazon Linux 2
  • Open Source Linux Kernel
  • Red Hat Enterprise Linux
  • Ubuntu Linux
  • SUSE Linux
  • Oracle Linux
  • SUSE openSUSE
  • RESF Rocky Linux
  • Microsoft Azure
  • Dell Secure Connect Gateway
  • IBM QRadar SIEM
  • IBM Security Verify Access
  • Dell NetWorker

Productinfo

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Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.1
VulDB Meta Temp Score: 5.0

VulDB Base Score: 4.8
VulDB Temp Score: 4.6
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 5.5
NVD Vector: 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Null pointer dereference
CWE: CWE-476 / CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 261576
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2025-38684

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 5.10.241/5.15.190/6.1.149/6.6.103/6.12.43/6.15.11/6.16.2/6.17-rc2
Patch: bdfddcde86e8b9245d9c0c2efe2b6fe8dcf6bf41/be9692dafdfb36d9c43afd9d4e1d9d9ba8e7b51b/97ec167cd2e8a81a2d87331a2ed92daf007542c8/84a24fb446ee07b22b64aae6f0e3f4a38266310a/5b3b346bc4c2aa2c428735438a11989d251f32f1/d69f4a258cd91b3bcef7089eb0401005aae2aed5/970c1c731c4ede46d05f5b0355724d1e400cfbca/87c6efc5ce9c126ae4a781bc04504b83780e3650

Timelineinfo

04/16/2025 CVE reserved
09/04/2025 +141 days Advisory disclosed
09/04/2025 +0 days VulDB entry created
02/10/2026 +159 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2025-38684 (🔒)
GCVE (CVE): GCVE-0-2025-38684
GCVE (VulDB): GCVE-100-322537
CERT Bund: WID-SEC-2025-1976 - Linux Kernel: Mehrere Schwachstellen erm&ouml;glichen Denial of Service

Entryinfo

Created: 09/04/2025 18:25
Updated: 02/10/2026 04:39
Changes: 09/04/2025 18:25 (58), 09/05/2025 12:08 (7), 09/07/2025 21:37 (2), 09/29/2025 11:28 (1), 10/08/2025 14:09 (1), 12/02/2025 07:19 (1), 01/09/2026 06:57 (12), 01/14/2026 17:34 (1), 02/10/2026 04:39 (1)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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