CVE-2026-68377
Full vulnerability record from the local CVENow database.
Description
In the Linux kernel, the following vulnerability has been resolved: net/sched: act_tunnel_key: Defer dst_release to RCU callback Fix a race-condition use-after-free in tunnel_key_release_params(). The function releases the metadata_dst of the old params synchronously via dst_release() while deferring the params struct free with kfree_rcu(). A concurrent tunnel_key_act() reader on the datapath may still hold the old params pointer (under rcu_read_lock_bh) and proceed to call dst_clone(¶ms->tcft_enc_metadata->dst) after the writer's dst_release has already pushed the dst's rcuref to RCUREF_DEAD. [email protected] produced a poc which i (and Victor) verified that KASAN reports: ================================================================== BUG: KASAN: slab-use-after-free in instrument_atomic_read_write include/linux/instrumented.h:112 BUG: KASAN: slab-use-after-free in atomic_sub_return_release include/linux/atomic/atomic-instrumented.h:326 BUG: KASAN: slab-use-after-free in __rcuref_put include/linux/rcuref.h:109 BUG: KASAN: slab-use-after-free in rcuref_put include/linux/rcuref.h:173 BUG: KASAN: slab-use-after-free in dst_release+0x5b/0x370 net/core/dst.c:168 Write of size 4 at addr ffff88806158de40 by task poc/9388 CPU: 0 UID: 0 PID: 9388 Comm: poc Tainted: G W 7.1.0-rc7 #7 PREEMPT(lazy) Tainted: [W]=WARN Hardware name: QEMU Ubuntu 25.10 PC v2 (i440FX + PIIX, + 10.1 machine, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Call Trace: <TASK> __dump_stack lib/dump_stack.c:94 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 print_report+0x139/0x4ad mm/kasan/report.c:482 kasan_report+0xe4/0x1d0 mm/kasan/report.c:595 check_region_inline mm/kasan/generic.c:186 kasan_check_range+0x125/0x200 mm/kasan/generic.c:200 instrument_atomic_read_write include/linux/instrumented.h:112 atomic_sub_return_release include/linux/atomic/atomic-instrumented.h:326 __rcuref_put include/linux/rcuref.h:109 rcuref_put include/linux/rcuref.h:173 dst_release+0x5b/0x370 net/core/dst.c:168 refdst_drop include/net/dst.h:272 skb_dst_drop include/net/dst.h:284 skb_release_head_state+0x293/0x400 net/core/skbuff.c:1163 skb_release_all net/core/skbuff.c:1187 [..] Allocated by task 9391: kasan_save_stack+0x30/0x50 mm/kasan/common.c:57 kasan_save_track+0x14/0x30 mm/kasan/common.c:78 poison_kmalloc_redzone mm/kasan/common.c:398 __kasan_kmalloc+0x9a/0xb0 mm/kasan/common.c:415 kasan_kmalloc include/linux/kasan.h:263 __do_kmalloc_node mm/slub.c:5296 __kmalloc_noprof+0x2f1/0x830 mm/slub.c:5308 kmalloc_noprof include/linux/slab.h:954 kzalloc_noprof include/linux/slab.h:1188 offload_action_alloc+0x2f/0x130 net/core/flow_offload.c:35 tcf_action_offload_add_ex+0x1ba/0x880 net/sched/act_api.c:258 tcf_action_offload_add net/sched/act_api.c:293 tcf_action_init+0x66e/0xa20 net/sched/act_api.c:1547 tcf_action_add+0xf6/0x5d0 net/sched/act_api.c:2101 [..] Freed by task 9391: kasan_save_stack+0x30/0x50 mm/kasan/common.c:57 kasan_save_track+0x14/0x30 mm/kasan/common.c:78 kasan_save_free_info+0x3b/0x70 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:253 __kasan_slab_free+0x6b/0x90 mm/kasan/common.c:285 kasan_slab_free include/linux/kasan.h:235 slab_free_hook mm/slub.c:2689 slab_free mm/slub.c:6251 kfree+0x21f/0x6b0 mm/slub.c:6566 tcf_action_offload_add_ex+0x4ad/0x880 net/sched/act_api.c:284 tcf_action_offload_add net/sched/act_api.c:293 tcf_action_init+0x66e/0xa20 net/sched/act_api.c:1547 tcf_action_add+0xf6/0x5d0 net/sched/act_api.c:2101 The buggy address belongs to the object at ffff88806158de00 which belongs to the cache kmalloc-256 of size 256 The buggy address is located 64 bytes inside of freed 256-byte region [ffff88806158de00, ffff88806158df00) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88806158d600 pfn:0x6158c head: order:1 mapcount:0 entire_map ---truncated---
View original CVE JSON
{
"id": "CVE-2026-68377",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2026-08-10T13:20:30.647",
"lastModified": "2026-10-19T22:17:15.410",
"vulnStatus": "Received",
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: act_tunnel_key: Defer dst_release to RCU callback\n\nFix a race-condition use-after-free in tunnel_key_release_params().\n\nThe function releases the metadata_dst of the old params synchronously\nvia dst_release() while deferring the params struct free with\nkfree_rcu(). A concurrent tunnel_key_act() reader on the datapath may\nstill hold the old params pointer (under rcu_read_lock_bh) and proceed\nto call dst_clone(¶ms->tcft_enc_metadata->dst) after the writer's\ndst_release has already pushed the dst's rcuref to RCUREF_DEAD.\n\[email protected] produced a poc which i (and Victor) verified\nthat KASAN reports:\n\n==================================================================\nBUG: KASAN: slab-use-after-free in instrument_atomic_read_write include/linux/instrumented.h:112\nBUG: KASAN: slab-use-after-free in atomic_sub_return_release include/linux/atomic/atomic-instrumented.h:326\nBUG: KASAN: slab-use-after-free in __rcuref_put include/linux/rcuref.h:109\nBUG: KASAN: slab-use-after-free in rcuref_put include/linux/rcuref.h:173\nBUG: KASAN: slab-use-after-free in dst_release+0x5b/0x370 net/core/dst.c:168\nWrite of size 4 at addr ffff88806158de40 by task poc/9388\n\nCPU: 0 UID: 0 PID: 9388 Comm: poc Tainted: G W 7.1.0-rc7 #7 PREEMPT(lazy)\nTainted: [W]=WARN\nHardware name: QEMU Ubuntu 25.10 PC v2 (i440FX + PIIX, + 10.1 machine, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014\nCall Trace:\n <TASK>\n __dump_stack lib/dump_stack.c:94\n dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120\n print_address_description mm/kasan/report.c:378\n print_report+0x139/0x4ad mm/kasan/report.c:482\n kasan_report+0xe4/0x1d0 mm/kasan/report.c:595\n check_region_inline mm/kasan/generic.c:186\n kasan_check_range+0x125/0x200 mm/kasan/generic.c:200\n instrument_atomic_read_write include/linux/instrumented.h:112\n atomic_sub_return_release include/linux/atomic/atomic-instrumented.h:326\n __rcuref_put include/linux/rcuref.h:109\n rcuref_put include/linux/rcuref.h:173\n dst_release+0x5b/0x370 net/core/dst.c:168\n refdst_drop include/net/dst.h:272\n skb_dst_drop include/net/dst.h:284\n skb_release_head_state+0x293/0x400 net/core/skbuff.c:1163\n skb_release_all net/core/skbuff.c:1187\n[..]\nAllocated by task 9391:\n kasan_save_stack+0x30/0x50 mm/kasan/common.c:57\n kasan_save_track+0x14/0x30 mm/kasan/common.c:78\n poison_kmalloc_redzone mm/kasan/common.c:398\n __kasan_kmalloc+0x9a/0xb0 mm/kasan/common.c:415\n kasan_kmalloc include/linux/kasan.h:263\n __do_kmalloc_node mm/slub.c:5296\n __kmalloc_noprof+0x2f1/0x830 mm/slub.c:5308\n kmalloc_noprof include/linux/slab.h:954\n kzalloc_noprof include/linux/slab.h:1188\n offload_action_alloc+0x2f/0x130 net/core/flow_offload.c:35\n tcf_action_offload_add_ex+0x1ba/0x880 net/sched/act_api.c:258\n tcf_action_offload_add net/sched/act_api.c:293\n tcf_action_init+0x66e/0xa20 net/sched/act_api.c:1547\n tcf_action_add+0xf6/0x5d0 net/sched/act_api.c:2101\n[..]\nFreed by task 9391:\n kasan_save_stack+0x30/0x50 mm/kasan/common.c:57\n kasan_save_track+0x14/0x30 mm/kasan/common.c:78\n kasan_save_free_info+0x3b/0x70 mm/kasan/generic.c:584\n poison_slab_object mm/kasan/common.c:253\n __kasan_slab_free+0x6b/0x90 mm/kasan/common.c:285\n kasan_slab_free include/linux/kasan.h:235\n slab_free_hook mm/slub.c:2689\n slab_free mm/slub.c:6251\n kfree+0x21f/0x6b0 mm/slub.c:6566\n tcf_action_offload_add_ex+0x4ad/0x880 net/sched/act_api.c:284\n tcf_action_offload_add net/sched/act_api.c:293\n tcf_action_init+0x66e/0xa20 net/sched/act_api.c:1547\n tcf_action_add+0xf6/0x5d0 net/sched/act_api.c:2101\n\nThe buggy address belongs to the object at ffff88806158de00\n which belongs to the cache kmalloc-256 of size 256\nThe buggy address is located 64 bytes inside of\n freed 256-byte region [ffff88806158de00, ffff88806158df00)\n\nThe buggy address belongs to the physical page:\npage: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88806158d600 pfn:0x6158c\nhead: order:1 mapcount:0 entire_map\n---truncated---"
}
],
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "unaffected",
"programFiles": [
"net/sched/act_tunnel_key.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
"version": "9174c3df1cd181c14913138d50ccbe539bb08335",
"lessThan": "b5931f020b681fdcb9378262d89b61cb3c7ebbf8",
"versionType": "git",
"status": "affected"
},
{
"version": "9174c3df1cd181c14913138d50ccbe539bb08335",
"lessThan": "389d03992dabb80488228e8119b9dd6d0f58e1a6",
"versionType": "git",
"status": "affected"
},
{
"version": "9174c3df1cd181c14913138d50ccbe539bb08335",
"lessThan": "676ad6aa7cec89a08d2a5ce3cd5959e313f29733",
"versionType": "git",
"status": "affected"
},
{
"version": "9174c3df1cd181c14913138d50ccbe539bb08335",
"lessThan": "531dbb5bb98e52ad26be7e90f9f8bec707c5bd0e",
"versionType": "git",
"status": "affected"
},
{
"version": "9174c3df1cd181c14913138d50ccbe539bb08335",
"lessThan": "2200a00ff247f70f5dcdb4e6f14b0d48ddac5467",
"versionType": "git",
"status": "affected"
},
{
"version": "9174c3df1cd181c14913138d50ccbe539bb08335",
"lessThan": "fed1b1ddab41a0e7a462ac690a0c8af6ff793624",
"versionType": "git",
"status": "affected"
},
{
"version": "9174c3df1cd181c14913138d50ccbe539bb08335",
"lessThan": "2791a501da508b704a617b4dba29db54a65bc9f7",
"versionType": "git",
"status": "affected"
},
{
"version": "9174c3df1cd181c14913138d50ccbe539bb08335",
"lessThan": "f1f5c8a3955f8fda3f84ed883ac8daa1847e724c",
"versionType": "git",
"status": "affected"
},
{
"version": "02239e797ac75f89a05622a27d04695f08c1ca89",
"versionType": "git",
"status": "affected"
},
{
"version": "ca9b7a65a2c97579fcdd509d454d48e3a5c49af8",
"versionType": "git",
"status": "affected"
},
{
"version": "4.19.19",
"lessThan": "4.20",
"versionType": "semver",
"status": "affected"
},
{
"version": "4.20.6",
"lessThan": "4.21",
"versionType": "semver",
"status": "affected"
}
]
},
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "affected",
"programFiles": [
"net/sched/act_tunnel_key.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
"version": "5.0",
"status": "affected"
},
{
"version": "0",
"lessThan": "5.0",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "5.10.265",
"lessThanOrEqual": "5.10.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "5.15.216",
"lessThanOrEqual": "5.15.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.1.183",
"lessThanOrEqual": "6.1.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.6.148",
"lessThanOrEqual": "6.6.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.12.101",
"lessThanOrEqual": "6.12.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.18.42",
"lessThanOrEqual": "6.18.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "7.1.6",
"lessThanOrEqual": "7.1.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "7.2",
"lessThanOrEqual": "*",
"versionType": "original_commit_for_fix",
"status": "unaffected"
}
]
}
]
}
],
"metrics": {
"cvssMetricV31": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"type": "Secondary",
"cvssData": {
"version": "3.1",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"baseScore": 7.8,
"baseSeverity": "HIGH",
"attackVector": "LOCAL",
"attackComplexity": "LOW",
"privilegesRequired": "LOW",
"userInteraction": "NONE",
"scope": "UNCHANGED",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"availabilityImpact": "HIGH"
},
"exploitabilityScore": 1.8,
"impactScore": 5.9
}
],
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"timestamp": "2026-10-16T15:47:38.441696Z",
"id": "CVE-2026-68377",
"options": [
{
"exploitation": "none"
},
{
"automatable": "no"
},
{
"technicalImpact": "total"
}
],
"role": "CISA Coordinator",
"version": "2.0.3"
}
}
]
},
"weaknesses": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"type": "Secondary",
"description": [
{
"lang": "en",
"value": "CWE-416"
}
]
}
],
"references": [
{
"url": "https://git.kernel.org/stable/c/2200a00ff247f70f5dcdb4e6f14b0d48ddac5467",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/2791a501da508b704a617b4dba29db54a65bc9f7",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/389d03992dabb80488228e8119b9dd6d0f58e1a6",
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{
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{
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{
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{
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{
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}
]
}