CVE-2026-64543
Full vulnerability record from the local CVENow database.
Description
In the Linux kernel, the following vulnerability has been resolved: tipc: fix use-after-free of the discoverer in tipc_disc_rcv() bearer_disable() frees b->disc with tipc_disc_delete()'s plain kfree(), but tipc_disc_rcv() still dereferences b->disc in RX softirq under rcu_read_lock() (tipc_udp_recv -> tipc_rcv -> tipc_disc_rcv). L2 bearers are safe thanks to the synchronize_net() in tipc_disable_l2_media(), but the UDP bearer defers that call to the cleanup_bearer() workqueue, so the discoverer is freed with no grace period: BUG: KASAN: slab-use-after-free in tipc_disc_rcv (net/tipc/discover.c:149) Read of size 8 at addr ffff88802348b728 by task poc_tipc/184 <IRQ> tipc_disc_rcv (net/tipc/discover.c:149) tipc_rcv (net/tipc/node.c:2126) tipc_udp_recv (net/tipc/udp_media.c:391) udp_rcv (net/ipv4/udp.c:2643) ip_local_deliver_finish (net/ipv4/ip_input.c:241) </IRQ> Freed by task 181: kfree (mm/slub.c:6565) bearer_disable (net/tipc/bearer.c:418) tipc_nl_bearer_disable (net/tipc/bearer.c:1001) The bearer is freed with kfree_rcu(); free the discoverer the same way. Add an rcu_head to struct tipc_discoverer and free it and its skb from an RCU callback. Because the RCU callback (tipc_disc_free_rcu) lives in module text, a call_rcu() that is still pending when the tipc module is unloaded would invoke a freed function. Add an rcu_barrier() to tipc_exit() after the bearer subsystem has been torn down, so all pending discoverer callbacks have run before the module text goes away. Reachable from an unprivileged user namespace: the TIPCv2 genl family is netnsok and its bearer commands have no GENL_ADMIN_PERM. Needs CONFIG_TIPC and CONFIG_TIPC_MEDIA_UDP.
Severity
HIGH
CVSS score
7.8
(v3.1)
Vulnerability status
Received
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2026-07-27 21:17:06.850000
Last modified
2026-10-19 21:17:44.180000
View original CVE JSON
{
"id": "CVE-2026-64543",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2026-07-27T21:17:06.850",
"lastModified": "2026-10-19T21:17:44.180",
"vulnStatus": "Received",
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntipc: fix use-after-free of the discoverer in tipc_disc_rcv()\n\nbearer_disable() frees b->disc with tipc_disc_delete()'s plain kfree(),\nbut tipc_disc_rcv() still dereferences b->disc in RX softirq under\nrcu_read_lock() (tipc_udp_recv -> tipc_rcv -> tipc_disc_rcv).\n\nL2 bearers are safe thanks to the synchronize_net() in\ntipc_disable_l2_media(), but the UDP bearer defers that call to the\ncleanup_bearer() workqueue, so the discoverer is freed with no grace\nperiod:\n\n BUG: KASAN: slab-use-after-free in tipc_disc_rcv (net/tipc/discover.c:149)\n Read of size 8 at addr ffff88802348b728 by task poc_tipc/184\n <IRQ>\n tipc_disc_rcv (net/tipc/discover.c:149)\n tipc_rcv (net/tipc/node.c:2126)\n tipc_udp_recv (net/tipc/udp_media.c:391)\n udp_rcv (net/ipv4/udp.c:2643)\n ip_local_deliver_finish (net/ipv4/ip_input.c:241)\n </IRQ>\n Freed by task 181:\n kfree (mm/slub.c:6565)\n bearer_disable (net/tipc/bearer.c:418)\n tipc_nl_bearer_disable (net/tipc/bearer.c:1001)\n\nThe bearer is freed with kfree_rcu(); free the discoverer the same way.\nAdd an rcu_head to struct tipc_discoverer and free it and its skb from an\nRCU callback.\n\nBecause the RCU callback (tipc_disc_free_rcu) lives in module text, a\ncall_rcu() that is still pending when the tipc module is unloaded would\ninvoke a freed function. Add an rcu_barrier() to tipc_exit() after the\nbearer subsystem has been torn down, so all pending discoverer callbacks\nhave run before the module text goes away.\n\nReachable from an unprivileged user namespace: the TIPCv2 genl family is\nnetnsok and its bearer commands have no GENL_ADMIN_PERM. Needs CONFIG_TIPC\nand CONFIG_TIPC_MEDIA_UDP."
}
],
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "unaffected",
"programFiles": [
"net/tipc/core.c",
"net/tipc/discover.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
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"lessThan": "380413cdfd29fb9fa486c82889132b680c4983c5",
"versionType": "git",
"status": "affected"
},
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"status": "affected"
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{
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},
{
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"defaultStatus": "affected",
"programFiles": [
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"net/tipc/discover.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
"version": "4.17",
"status": "affected"
},
{
"version": "0",
"lessThan": "4.17",
"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": "6.6.145",
"lessThanOrEqual": "6.6.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.12.97",
"lessThanOrEqual": "6.12.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.18.40",
"lessThanOrEqual": "6.18.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "7.1.5",
"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": "2026-10-16T15:42:12.338756Z",
"id": "CVE-2026-64543",
"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": [
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"url": "https://git.kernel.org/stable/c/1579342d71133da7f00daa02c75cebec7372097b",
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}