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CVE-2026-72390 (GCVE-0-2026-72390)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:56 – Updated: 2026-08-17 05:43
VLAI
Title
net/sched: sch_teql: Introduce slaves_lock to avoid race condition and UAF
Summary
In the Linux kernel, the following vulnerability has been resolved: net/sched: sch_teql: Introduce slaves_lock to avoid race condition and UAF The teql master->slaves singly linked list is not protected against multiple writes. It can be mod'ed concurently from teql_master_xmit(), teql_dequeue(), teql_init() and teql_destroy() without holding any list lock or RCU protection. zdi-disclosures@trendmicro.com has demonstrated that the qdisc is freed after an RCU grace period, but teql_master_xmit() running on another CPU can still hold a stale pointer into the list, resulting in a slab-use-after-free: BUG: KASAN: slab-use-after-free in teql_master_xmit+0xf0f/0x16b0 Read of size 8 at addr ffff888013fb0440 by task poc/332 Freed 512-byte region [ffff888013fb0400, ffff888013fb0600) (kmalloc-512) The fix? Add a per-master slaves_lock spinlock that serializes all mutations of master->slaves and the NEXT_SLAVE() links in teql_destroy() and teql_qdisc_init(). teql_master_xmit() also takes the same slaves_lock around those updates. Annotate master->slaves and the per-slave ->next pointer with __rcu and use the appropriate RCU accessors everywhere they are touched: rcu_assign_pointer() on the writer side (under slaves_lock), rcu_dereference_protected() for the writer-side loads (also under slaves_lock), rcu_dereference_bh() for the loads in teql_master_xmit() and rtnl_dereference() for the loads in teql_master_open()/teql_master_mtu(), which run under RTNL. Pair this with rcu_read_lock_bh()/rcu_read_unlock_bh() around the list traversal in teql_master_xmit(), so that readers either observe a fully linked list or are deferred until the in-flight mutation completes. The two early-return paths in teql_master_xmit() are updated to release the RCU-bh read-side critical section before returning, since leaving it held would disable BH on that CPU for good.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 03c67781254c574ae7fa75e881239a78473bdf42 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 735567bde7401f82b064f9f107b52ee1bf84ed8c (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 11402e6e18e96df615cbcc58157818dd604b23ff (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 9b7d05cbaa60108642402100efa6aa288dd33023 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < b26aa9d993537a4c3167d8ceead3b7c69c3a0aac (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < e5b811fe793166aecc59b085c1b7c31262ef2316 (git)
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Linux Linux Affected: 2.6.12
Unaffected: 0 , < 2.6.12 (semver)
Unaffected: 6.1.178 , ≤ 6.1.* (semver)
Unaffected: 6.6.145 , ≤ 6.6.* (semver)
Unaffected: 6.12.97 , ≤ 6.12.* (semver)
Unaffected: 6.18.40 , ≤ 6.18.* (semver)
Unaffected: 7.1.5 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: sch_teql: Introduce slaves_lock to avoid race condition and UAF\n\nThe teql master-\u003eslaves singly linked list is not protected against\nmultiple writes. It can be mod\u0027ed concurently from teql_master_xmit(),\nteql_dequeue(), teql_init() and teql_destroy() without holding any list\nlock or RCU protection.\n\nzdi-disclosures@trendmicro.com has demonstrated that the qdisc is freed\nafter an RCU grace period, but teql_master_xmit() running on another\nCPU can still hold a stale pointer into the list, resulting in a\nslab-use-after-free:\n\nBUG: KASAN: slab-use-after-free in teql_master_xmit+0xf0f/0x16b0\nRead of size 8 at addr ffff888013fb0440 by task poc/332\nFreed 512-byte region [ffff888013fb0400, ffff888013fb0600) (kmalloc-512)\n\nThe fix?\nAdd a per-master slaves_lock spinlock that serializes all mutations of\nmaster-\u003eslaves and the NEXT_SLAVE() links in teql_destroy() and\nteql_qdisc_init(). teql_master_xmit() also takes the same slaves_lock\naround those updates.\nAnnotate master-\u003eslaves and the per-slave -\u003enext pointer with __rcu and\nuse the appropriate RCU accessors everywhere they are touched:\nrcu_assign_pointer() on the writer side (under slaves_lock),\nrcu_dereference_protected() for the writer-side loads (also under\nslaves_lock), rcu_dereference_bh() for the loads in teql_master_xmit() and\nrtnl_dereference() for the loads in teql_master_open()/teql_master_mtu(),\nwhich run under RTNL.\nPair this with rcu_read_lock_bh()/rcu_read_unlock_bh() around the list\ntraversal in teql_master_xmit(), so that readers either observe a fully\nlinked list or are deferred until the in-flight mutation completes. The two\nearly-return paths in teql_master_xmit() are updated to release the RCU-bh\nread-side critical section before returning, since leaving it held would\ndisable BH on that CPU for good."
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              "value": "AV:L - Exploitation requires local rtnetlink tc/qdisc operations (RTM_NEWQDISC/RTM_DELQDISC) to attach or tear down TEQL slaves and local packet injection through teql0 to drive teql_master_xmit/teql_dequeue; remote peers cannot reach these control paths without prior CAP_NET_ADMIN setup.\nAC:L - The attacker controls both sides of the race by concurrently churning TEQL slave qdiscs via netlink teardown/re-add while flooding teql0 to keep teql_master_xmit traversing master-\u003eslaves; Trend Micro demonstrated reliable slab-use-after-free under this attacker-driven timing.\nPR:L - Configuring and deleting qdiscs requires CAP_NET_ADMIN, but rtnetlink checks netlink_net_capable() against the network namespace user_ns, so an unprivileged local user can obtain CAP_NET_ADMIN via user/network namespaces (unshare -Urn) without init-namespace root.\nUI:N - No victim interaction is required; the attacker programmatically loads/configures TEQL, starts transmit workers, and races qdisc deletion in parallel to trigger the use-after-free.\nS:U - Impact is kernel memory corruption and potential privilege escalation within the same kernel security domain; it does not inherently cross VM, container host, or IOMMU boundaries without separate further exploitation.\nC:H - Demonstrated slab-use-after-free reads through a stale Qdisc pointer in teql_master_xmit (8-byte read from a freed kmalloc-512 object); UAF on Qdisc structures enables heap spraying and arbitrary kernel memory disclosure.\nI:H - Use-after-free of the Qdisc object allows reallocating attacker-controlled data into the freed slab, corrupting list traversal and adjacent qdisc fields to obtain arbitrary kernel write primitives and potential code execution.\nA:H - The bug causes kernel oops/panic from dereferencing freed Qdisc memory during teql_master_xmit list walks; KASAN confirmed slab-use-after-free, and repeated triggering can deny service on affected systems."
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It can be mod\u0027ed concurently from teql_master_xmit(),\\nteql_dequeue(), teql_init() and teql_destroy() without holding any list\\nlock or RCU protection.\\n\\nzdi-disclosures@trendmicro.com has demonstrated that the qdisc is freed\\nafter an RCU grace period, but teql_master_xmit() running on another\\nCPU can still hold a stale pointer into the list, resulting in a\\nslab-use-after-free:\\n\\nBUG: KASAN: slab-use-after-free in teql_master_xmit+0xf0f/0x16b0\\nRead of size 8 at addr ffff888013fb0440 by task poc/332\\nFreed 512-byte region [ffff888013fb0400, ffff888013fb0600) (kmalloc-512)\\n\\nThe fix?\\nAdd a per-master slaves_lock spinlock that serializes all mutations of\\nmaster-\u003eslaves and the NEXT_SLAVE() links in teql_destroy() and\\nteql_qdisc_init(). teql_master_xmit() also takes the same slaves_lock\\naround those updates.\\nAnnotate master-\u003eslaves and the per-slave -\u003enext pointer with __rcu and\\nuse the appropriate RCU accessors everywhere they are touched:\\nrcu_assign_pointer() on the writer side (under slaves_lock),\\nrcu_dereference_protected() for the writer-side loads (also under\\nslaves_lock), rcu_dereference_bh() for the loads in teql_master_xmit() and\\nrtnl_dereference() for the loads in teql_master_open()/teql_master_mtu(),\\nwhich run under RTNL.\\nPair this with rcu_read_lock_bh()/rcu_read_unlock_bh() around the list\\ntraversal in teql_master_xmit(), so that readers either observe a fully\\nlinked list or are deferred until the in-flight mutation completes. The two\\nearly-return paths in teql_master_xmit() are updated to release the RCU-bh\\nread-side critical section before returning, since leaving it held would\\ndisable BH on that CPU for good.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"net/sched/sch_teql.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\",\"lessThan\":\"03c67781254c574ae7fa75e881239a78473bdf42\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\",\"lessThan\":\"735567bde7401f82b064f9f107b52ee1bf84ed8c\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\",\"lessThan\":\"11402e6e18e96df615cbcc58157818dd604b23ff\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\",\"lessThan\":\"9b7d05cbaa60108642402100efa6aa288dd33023\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\",\"lessThan\":\"b26aa9d993537a4c3167d8ceead3b7c69c3a0aac\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\",\"lessThan\":\"e5b811fe793166aecc59b085c1b7c31262ef2316\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"net/sched/sch_teql.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"2.6.12\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"2.6.12\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.1.178\",\"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}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/03c67781254c574ae7fa75e881239a78473bdf42\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/11402e6e18e96df615cbcc58157818dd604b23ff\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/735567bde7401f82b064f9f107b52ee1bf84ed8c\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/9b7d05cbaa60108642402100efa6aa288dd33023\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/b26aa9d993537a4c3167d8ceead3b7c69c3a0aac\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/e5b811fe793166aecc59b085c1b7c31262ef2316\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-19T17:43:32+00:00",
      "cve": "CVE-2026-72390",
      "id": "CVE-2026-72390",
      "initial_release_date": "2026-08-15T00:00:00+00:00",
      "product_status:known_affected": "90",
      "product_status:known_not_affected": "184",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: net/sched: sch_teql: Introduce slaves_lock to avoid race condition and UAF",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-72390.json",
      "version": "3"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


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