Linux Kernel up to 6.19-rc4 qdisc_get null pointer dereference

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5.0$0-$5k0.00

Summaryinfo

A vulnerability described as critical has been identified in Linux Kernel up to 6.19-rc4. Affected by this vulnerability is the function qdisc_get. The manipulation results in null pointer dereference. This vulnerability is cataloged as CVE-2026-22976. There is no exploit available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability classified as critical has been found in Linux Kernel up to 6.19-rc4. Affected is the function qdisc_get. The manipulation with an unknown input leads to a null pointer dereference vulnerability. CWE is classifying the issue as 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. This is going to have an impact on availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: net/sched: sch_qfq: Fix NULL deref when deactivating inactive aggregate in qfq_reset `qfq_class->leaf_qdisc->q.qlen > 0` does not imply that the class itself is active. Two qfq_class objects may point to the same leaf_qdisc. This happens when: 1. one QFQ qdisc is attached to the dev as the root qdisc, and 2. another QFQ qdisc is temporarily referenced (e.g., via qdisc_get() / qdisc_put()) and is pending to be destroyed, as in function tc_new_tfilter. When packets are enqueued through the root QFQ qdisc, the shared leaf_qdisc->q.qlen increases. At the same time, the second QFQ qdisc triggers qdisc_put and qdisc_destroy: the qdisc enters qfq_reset() with its own q->q.qlen == 0, but its class's leaf qdisc->q.qlen > 0. Therefore, the qfq_reset would wrongly deactivate an inactive aggregate and trigger a null-deref in qfq_deactivate_agg: [ 0.903172] BUG: kernel NULL pointer dereference, address: 0000000000000000 [ 0.903571] #PF: supervisor write access in kernel mode [ 0.903860] #PF: error_code(0x0002) - not-present page [ 0.904177] PGD 10299b067 P4D 10299b067 PUD 10299c067 PMD 0 [ 0.904502] Oops: Oops: 0002 [#1] SMP NOPTI [ 0.904737] CPU: 0 UID: 0 PID: 135 Comm: exploit Not tainted 6.19.0-rc3+ #2 NONE [ 0.905157] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.17.0-0-gb52ca86e094d-prebuilt.qemu.org 04/01/2014 [ 0.905754] RIP: 0010:qfq_deactivate_agg (include/linux/list.h:992 (discriminator 2) include/linux/list.h:1006 (discriminator 2) net/sched/sch_qfq.c:1367 (discriminator 2) net/sched/sch_qfq.c:1393 (discriminator 2)) [ 0.906046] Code: 0f 84 4d 01 00 00 48 89 70 18 8b 4b 10 48 c7 c2 ff ff ff ff 48 8b 78 08 48 d3 e2 48 21 f2 48 2b 13 48 8b 30 48 d3 ea 8b 4b 18 0 Code starting with the faulting instruction =========================================== 0: 0f 84 4d 01 00 00 je 0x153 6: 48 89 70 18 mov %rsi,0x18(%rax) a: 8b 4b 10 mov 0x10(%rbx),%ecx d: 48 c7 c2 ff ff ff ff mov $0xffffffffffffffff,%rdx 14: 48 8b 78 08 mov 0x8(%rax),%rdi 18: 48 d3 e2 shl %cl,%rdx 1b: 48 21 f2 and %rsi,%rdx 1e: 48 2b 13 sub (%rbx),%rdx 21: 48 8b 30 mov (%rax),%rsi 24: 48 d3 ea shr %cl,%rdx 27: 8b 4b 18 mov 0x18(%rbx),%ecx ... [ 0.907095] RSP: 0018:ffffc900004a39a0 EFLAGS: 00010246 [ 0.907368] RAX: ffff8881043a0880 RBX: ffff888102953340 RCX: 0000000000000000 [ 0.907723] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 [ 0.908100] RBP: ffff888102952180 R08: 0000000000000000 R09: 0000000000000000 [ 0.908451] R10: ffff8881043a0000 R11: 0000000000000000 R12: ffff888102952000 [ 0.908804] R13: ffff888102952180 R14: ffff8881043a0ad8 R15: ffff8881043a0880 [ 0.909179] FS: 000000002a1a0380(0000) GS:ffff888196d8d000(0000) knlGS:0000000000000000 [ 0.909572] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 0.909857] CR2: 0000000000000000 CR3: 0000000102993002 CR4: 0000000000772ef0 [ 0.910247] PKRU: 55555554 [ 0.910391] Call Trace: [ 0.910527] <TASK> [ 0.910638] qfq_reset_qdisc (net/sched/sch_qfq.c:357 net/sched/sch_qfq.c:1485) [ 0.910826] qdisc_reset (include/linux/skbuff.h:2195 include/linux/skbuff.h:2501 include/linux/skbuff.h:3424 include/linux/skbuff.h:3430 net/sched/sch_generic.c:1036) [ 0.911040] __qdisc_destroy (net/sched/sch_generic.c:1076) [ 0.911236] tc_new_tfilter (net/sched/cls_api.c:2447) [ 0.911447] rtnetlink_rcv_msg (net/core/rtnetlink.c:6958) [ 0.911663] ? __pfx_rtnetlink_rcv_msg (net/core/rtnetlink.c:6861) [ 0.911894] netlink_rcv_skb (net/netlink/af_netlink.c:2550) [ 0.912100] netlink_unicast (net/netlink/af_netlink.c:1319 net/netlink/af_netlink.c:1344) [ 0.912296] ? __alloc_skb (net/core/skbuff.c:706) [ 0.912484] netlink_sendmsg (net/netlink/af ---truncated---

The advisory is shared for download at git.kernel.org. This vulnerability is traded as CVE-2026-22976 since 01/13/2026. The exploitability is told to be difficult. There are known technical details, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 298924 (SUSE SLES12 : Recommended update for initial livepatch (SUSE-SU-2026:0473-1)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 5.10.248, 5.15.198, 6.1.161, 6.6.121, 6.12.66, 6.18.6 or 6.19-rc5 eliminates this vulnerability. Applying the patch 6116a83ec167d3ab1390cded854d237481f41b63/0809c4bc06c9c961222df29f2eccfd449304056f/cdb24200b043438a144df501f1ebbd926bb1a2c7/11bf9134613f6c71fc0ff36c5d8d33856f6ae3bb/43497313d0da3e12b5cfcd97aa17bf48ee663f95/51ffd447bc37bf1a5776b85523f51d2bc69977f6/c1d73b1480235731e35c81df70b08f4714a7d095 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 CNNVD (CNNVD-202601-3438), Tenable (298924) and CERT Bund (WID-SEC-2026-0184). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Affected

  • Open Source Linux Kernel

Productinfo

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Version

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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: 298924
Nessus Name: SUSE SLES12 : Recommended update for initial livepatch (SUSE-SU-2026:0473-1)

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 5.10.248/5.15.198/6.1.161/6.6.121/6.12.66/6.18.6/6.19-rc5
Patch: 6116a83ec167d3ab1390cded854d237481f41b63/0809c4bc06c9c961222df29f2eccfd449304056f/cdb24200b043438a144df501f1ebbd926bb1a2c7/11bf9134613f6c71fc0ff36c5d8d33856f6ae3bb/43497313d0da3e12b5cfcd97aa17bf48ee663f95/51ffd447bc37bf1a5776b85523f51d2bc69977f6/c1d73b1480235731e35c81df70b08f4714a7d095

Timelineinfo

01/13/2026 CVE reserved
01/21/2026 +8 days Advisory disclosed
01/21/2026 +0 days VulDB entry created
06/02/2026 +132 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-22976 (🔒)
GCVE (CVE): GCVE-0-2026-22976
GCVE (VulDB): GCVE-100-342144
CERT Bund: WID-SEC-2026-0184 - Linux Kernel: Schwachstelle erm&ouml;glicht Denial of Service
CNNVD: CNNVD-202601-3438 - Linux kernel 安全漏洞

Entryinfo

Created: 01/21/2026 08:34
Updated: 06/02/2026 19:21
Changes: 01/21/2026 08:34 (58), 01/22/2026 01:07 (7), 01/23/2026 11:32 (6), 01/27/2026 09:25 (1), 02/14/2026 21:27 (2), 02/26/2026 23:51 (11), 06/02/2026 19:21 (1)
Complete: 🔍
Cache ID: 216::103

VulDB is the best source for vulnerability data and more expert information about this specific topic.

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