{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-22976", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-01-13T15:37:45.935Z", "datePublished": "2026-01-21T06:57:23.939Z", "dateUpdated": "2026-01-21T06:57:23.939Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-01-21T06:57:23.939Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: sch_qfq: Fix NULL deref when deactivating inactive aggregate in qfq_reset\n\n`qfq_class->leaf_qdisc->q.qlen > 0` does not imply that the class\nitself is active.\n\nTwo qfq_class objects may point to the same leaf_qdisc. This happens\nwhen:\n\n1. one QFQ qdisc is attached to the dev as the root qdisc, and\n\n2. another QFQ qdisc is temporarily referenced (e.g., via qdisc_get()\n/ qdisc_put()) and is pending to be destroyed, as in function\ntc_new_tfilter.\n\nWhen packets are enqueued through the root QFQ qdisc, the shared\nleaf_qdisc->q.qlen increases. At the same time, the second QFQ\nqdisc triggers qdisc_put and qdisc_destroy: the qdisc enters\nqfq_reset() with its own q->q.qlen == 0, but its class's leaf\nqdisc->q.qlen > 0. Therefore, the qfq_reset would wrongly deactivate\nan inactive aggregate and trigger a null-deref in qfq_deactivate_agg:\n\n[ 0.903172] BUG: kernel NULL pointer dereference, address: 0000000000000000\n[ 0.903571] #PF: supervisor write access in kernel mode\n[ 0.903860] #PF: error_code(0x0002) - not-present page\n[ 0.904177] PGD 10299b067 P4D 10299b067 PUD 10299c067 PMD 0\n[ 0.904502] Oops: Oops: 0002 [#1] SMP NOPTI\n[ 0.904737] CPU: 0 UID: 0 PID: 135 Comm: exploit Not tainted 6.19.0-rc3+ #2 NONE\n[ 0.905157] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.17.0-0-gb52ca86e094d-prebuilt.qemu.org 04/01/2014\n[ 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))\n[ 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\n\nCode starting with the faulting instruction\n===========================================\n 0:\t0f 84 4d 01 00 00 \tje 0x153\n 6:\t48 89 70 18 \tmov %rsi,0x18(%rax)\n a:\t8b 4b 10 \tmov 0x10(%rbx),%ecx\n d:\t48 c7 c2 ff ff ff ff \tmov $0xffffffffffffffff,%rdx\n 14:\t48 8b 78 08 \tmov 0x8(%rax),%rdi\n 18:\t48 d3 e2 \tshl %cl,%rdx\n 1b:\t48 21 f2 \tand %rsi,%rdx\n 1e:\t48 2b 13 \tsub (%rbx),%rdx\n 21:\t48 8b 30 \tmov (%rax),%rsi\n 24:\t48 d3 ea \tshr %cl,%rdx\n 27:\t8b 4b 18 \tmov 0x18(%rbx),%ecx\n\t...\n[ 0.907095] RSP: 0018:ffffc900004a39a0 EFLAGS: 00010246\n[ 0.907368] RAX: ffff8881043a0880 RBX: ffff888102953340 RCX: 0000000000000000\n[ 0.907723] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000\n[ 0.908100] RBP: ffff888102952180 R08: 0000000000000000 R09: 0000000000000000\n[ 0.908451] R10: ffff8881043a0000 R11: 0000000000000000 R12: ffff888102952000\n[ 0.908804] R13: ffff888102952180 R14: ffff8881043a0ad8 R15: ffff8881043a0880\n[ 0.909179] FS: 000000002a1a0380(0000) GS:ffff888196d8d000(0000) knlGS:0000000000000000\n[ 0.909572] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n[ 0.909857] CR2: 0000000000000000 CR3: 0000000102993002 CR4: 0000000000772ef0\n[ 0.910247] PKRU: 55555554\n[ 0.910391] Call Trace:\n[ 0.910527] <TASK>\n[ 0.910638] qfq_reset_qdisc (net/sched/sch_qfq.c:357 net/sched/sch_qfq.c:1485)\n[ 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)\n[ 0.911040] __qdisc_destroy (net/sched/sch_generic.c:1076)\n[ 0.911236] tc_new_tfilter (net/sched/cls_api.c:2447)\n[ 0.911447] rtnetlink_rcv_msg (net/core/rtnetlink.c:6958)\n[ 0.911663] ? __pfx_rtnetlink_rcv_msg (net/core/rtnetlink.c:6861)\n[ 0.911894] netlink_rcv_skb (net/netlink/af_netlink.c:2550)\n[ 0.912100] netlink_unicast (net/netlink/af_netlink.c:1319 net/netlink/af_netlink.c:1344)\n[ 0.912296] ? __alloc_skb (net/core/skbuff.c:706)\n[ 0.912484] netlink_sendmsg (net/netlink/af\n---truncated---"}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/sched/sch_qfq.c"], "versions": [{"version": "0545a3037773512d3448557ba048cebb73b3e4af", "lessThan": "6116a83ec167d3ab1390cded854d237481f41b63", "status": "affected", "versionType": "git"}, {"version": "0545a3037773512d3448557ba048cebb73b3e4af", "lessThan": "0809c4bc06c9c961222df29f2eccfd449304056f", "status": "affected", "versionType": "git"}, {"version": "0545a3037773512d3448557ba048cebb73b3e4af", "lessThan": "cdb24200b043438a144df501f1ebbd926bb1a2c7", "status": "affected", "versionType": "git"}, {"version": "0545a3037773512d3448557ba048cebb73b3e4af", "lessThan": "11bf9134613f6c71fc0ff36c5d8d33856f6ae3bb", "status": "affected", "versionType": "git"}, {"version": "0545a3037773512d3448557ba048cebb73b3e4af", "lessThan": "43497313d0da3e12b5cfcd97aa17bf48ee663f95", "status": "affected", "versionType": "git"}, {"version": "0545a3037773512d3448557ba048cebb73b3e4af", "lessThan": "51ffd447bc37bf1a5776b85523f51d2bc69977f6", "status": "affected", "versionType": "git"}, {"version": "0545a3037773512d3448557ba048cebb73b3e4af", "lessThan": "c1d73b1480235731e35c81df70b08f4714a7d095", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/sched/sch_qfq.c"], "versions": [{"version": "3.0", "status": "affected"}, {"version": "0", "lessThan": "3.0", "status": "unaffected", "versionType": "semver"}, {"version": "5.10.248", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.15.198", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.1.161", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.121", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.66", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.6", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.19-rc5", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.0", "versionEndExcluding": "5.10.248"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.0", "versionEndExcluding": "5.15.198"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.0", "versionEndExcluding": "6.1.161"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.0", "versionEndExcluding": "6.6.121"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.0", "versionEndExcluding": "6.12.66"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.0", "versionEndExcluding": "6.18.6"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.0", "versionEndExcluding": "6.19-rc5"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/6116a83ec167d3ab1390cded854d237481f41b63"}, {"url": "https://git.kernel.org/stable/c/0809c4bc06c9c961222df29f2eccfd449304056f"}, {"url": "https://git.kernel.org/stable/c/cdb24200b043438a144df501f1ebbd926bb1a2c7"}, {"url": "https://git.kernel.org/stable/c/11bf9134613f6c71fc0ff36c5d8d33856f6ae3bb"}, {"url": "https://git.kernel.org/stable/c/43497313d0da3e12b5cfcd97aa17bf48ee663f95"}, {"url": "https://git.kernel.org/stable/c/51ffd447bc37bf1a5776b85523f51d2bc69977f6"}, {"url": "https://git.kernel.org/stable/c/c1d73b1480235731e35c81df70b08f4714a7d095"}], "title": "net/sched: sch_qfq: Fix NULL deref when deactivating inactive aggregate in qfq_reset", "x_generator": {"engine": "bippy-1.2.0"}}}}

{}

{"cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: sch_qfq: Fix NULL deref when deactivating inactive aggregate in qfq_reset\n\n`qfq_class->leaf_qdisc->q.qlen > 0` does not imply that the class\nitself is active.\n\nTwo qfq_class objects may point to the same leaf_qdisc. This happens\nwhen:\n\n1. one QFQ qdisc is attached to the dev as the root qdisc, and\n\n2. another QFQ qdisc is temporarily referenced (e.g., via qdisc_get()\n/ qdisc_put()) and is pending to be destroyed, as in function\ntc_new_tfilter.\n\nWhen packets are enqueued through the root QFQ qdisc, the shared\nleaf_qdisc->q.qlen increases. At the same time, the second QFQ\nqdisc triggers qdisc_put and qdisc_destroy: the qdisc enters\nqfq_reset() with its own q->q.qlen == 0, but its class's leaf\nqdisc->q.qlen > 0. Therefore, the qfq_reset would wrongly deactivate\nan inactive aggregate and trigger a null-deref in qfq_deactivate_agg:\n\n[ 0.903172] BUG: kernel NULL pointer dereference, address: 0000000000000000\n[ 0.903571] #PF: supervisor write access in kernel mode\n[ 0.903860] #PF: error_code(0x0002) - not-present page\n[ 0.904177] PGD 10299b067 P4D 10299b067 PUD 10299c067 PMD 0\n[ 0.904502] Oops: Oops: 0002 [#1] SMP NOPTI\n[ 0.904737] CPU: 0 UID: 0 PID: 135 Comm: exploit Not tainted 6.19.0-rc3+ #2 NONE\n[ 0.905157] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.17.0-0-gb52ca86e094d-prebuilt.qemu.org 04/01/2014\n[ 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))\n[ 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\n\nCode starting with the faulting instruction\n===========================================\n 0:\t0f 84 4d 01 00 00 \tje 0x153\n 6:\t48 89 70 18 \tmov %rsi,0x18(%rax)\n a:\t8b 4b 10 \tmov 0x10(%rbx),%ecx\n d:\t48 c7 c2 ff ff ff ff \tmov $0xffffffffffffffff,%rdx\n 14:\t48 8b 78 08 \tmov 0x8(%rax),%rdi\n 18:\t48 d3 e2 \tshl %cl,%rdx\n 1b:\t48 21 f2 \tand %rsi,%rdx\n 1e:\t48 2b 13 \tsub (%rbx),%rdx\n 21:\t48 8b 30 \tmov (%rax),%rsi\n 24:\t48 d3 ea \tshr %cl,%rdx\n 27:\t8b 4b 18 \tmov 0x18(%rbx),%ecx\n\t...\n[ 0.907095] RSP: 0018:ffffc900004a39a0 EFLAGS: 00010246\n[ 0.907368] RAX: ffff8881043a0880 RBX: ffff888102953340 RCX: 0000000000000000\n[ 0.907723] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000\n[ 0.908100] RBP: ffff888102952180 R08: 0000000000000000 R09: 0000000000000000\n[ 0.908451] R10: ffff8881043a0000 R11: 0000000000000000 R12: ffff888102952000\n[ 0.908804] R13: ffff888102952180 R14: ffff8881043a0ad8 R15: ffff8881043a0880\n[ 0.909179] FS: 000000002a1a0380(0000) GS:ffff888196d8d000(0000) knlGS:0000000000000000\n[ 0.909572] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n[ 0.909857] CR2: 0000000000000000 CR3: 0000000102993002 CR4: 0000000000772ef0\n[ 0.910247] PKRU: 55555554\n[ 0.910391] Call Trace:\n[ 0.910527] <TASK>\n[ 0.910638] qfq_reset_qdisc (net/sched/sch_qfq.c:357 net/sched/sch_qfq.c:1485)\n[ 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)\n[ 0.911040] __qdisc_destroy (net/sched/sch_generic.c:1076)\n[ 0.911236] tc_new_tfilter (net/sched/cls_api.c:2447)\n[ 0.911447] rtnetlink_rcv_msg (net/core/rtnetlink.c:6958)\n[ 0.911663] ? __pfx_rtnetlink_rcv_msg (net/core/rtnetlink.c:6861)\n[ 0.911894] netlink_rcv_skb (net/netlink/af_netlink.c:2550)\n[ 0.912100] netlink_unicast (net/netlink/af_netlink.c:1319 net/netlink/af_netlink.c:1344)\n[ 0.912296] ? __alloc_skb (net/core/skbuff.c:706)\n[ 0.912484] netlink_sendmsg (net/netlink/af\n---truncated---"}], "id": "CVE-2026-22976", "lastModified": "2026-01-21T07:16:01.433", "metrics": {}, "published": "2026-01-21T07:16:01.433", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/0809c4bc06c9c961222df29f2eccfd449304056f"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/11bf9134613f6c71fc0ff36c5d8d33856f6ae3bb"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/43497313d0da3e12b5cfcd97aa17bf48ee663f95"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/51ffd447bc37bf1a5776b85523f51d2bc69977f6"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/6116a83ec167d3ab1390cded854d237481f41b63"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/c1d73b1480235731e35c81df70b08f4714a7d095"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/cdb24200b043438a144df501f1ebbd926bb1a2c7"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{}

{}