{"id":"CVE-2026-72390","state":"PUBLISHED","title":"net/sched: sch_teql: Introduce slaves_lock to avoid race condition and UAF","description":"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->slaves singly linked list is not protected against\nmultiple writes. It can be mod'ed 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->slaves 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->slaves and the per-slave ->next 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.","publishedAt":"2026-08-15T05:56:19.186Z","updatedAt":"2026-10-16T18:55:21.250Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"03c67781254c574ae7fa75e881239a78473bdf42","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"735567bde7401f82b064f9f107b52ee1bf84ed8c","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"11402e6e18e96df615cbcc58157818dd604b23ff","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"9b7d05cbaa60108642402100efa6aa288dd33023","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"b26aa9d993537a4c3167d8ceead3b7c69c3a0aac","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"e5b811fe793166aecc59b085c1b7c31262ef2316","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sched/sch_teql.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.12","versionType":"semver"},{"version":"6.1.178","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.145","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.97","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.40","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.5","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sched/sch_teql.c"]}],"references":["https://git.kernel.org/stable/c/03c67781254c574ae7fa75e881239a78473bdf42","https://git.kernel.org/stable/c/735567bde7401f82b064f9f107b52ee1bf84ed8c","https://git.kernel.org/stable/c/11402e6e18e96df615cbcc58157818dd604b23ff","https://git.kernel.org/stable/c/9b7d05cbaa60108642402100efa6aa288dd33023","https://git.kernel.org/stable/c/b26aa9d993537a4c3167d8ceead3b7c69c3a0aac","https://git.kernel.org/stable/c/e5b811fe793166aecc59b085c1b7c31262ef2316"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:58.252Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/72xxx/CVE-2026-72390.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-72390","state":"PUBLISHED","datePublished":"2026-08-15T05:56:19.186Z","dateUpdated":"2026-10-16T18:55:21.250Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-08-09T03:40:39.924Z"},"containers":{"cna":{"title":"net/sched: sch_teql: Introduce slaves_lock to avoid race condition and UAF","descriptions":[{"lang":"en","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->slaves singly linked list is not protected against\nmultiple writes. It can be mod'ed 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->slaves 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->slaves and the per-slave ->next 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":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"03c67781254c574ae7fa75e881239a78473bdf42","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"735567bde7401f82b064f9f107b52ee1bf84ed8c","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"11402e6e18e96df615cbcc58157818dd604b23ff","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"9b7d05cbaa60108642402100efa6aa288dd33023","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"b26aa9d993537a4c3167d8ceead3b7c69c3a0aac","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"e5b811fe793166aecc59b085c1b7c31262ef2316","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sched/sch_teql.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.12","versionType":"semver"},{"version":"6.1.178","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.145","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.97","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.40","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.5","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sched/sch_teql.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/03c67781254c574ae7fa75e881239a78473bdf42"},{"url":"https://git.kernel.org/stable/c/735567bde7401f82b064f9f107b52ee1bf84ed8c"},{"url":"https://git.kernel.org/stable/c/11402e6e18e96df615cbcc58157818dd604b23ff"},{"url":"https://git.kernel.org/stable/c/9b7d05cbaa60108642402100efa6aa288dd33023"},{"url":"https://git.kernel.org/stable/c/b26aa9d993537a4c3167d8ceead3b7c69c3a0aac"},{"url":"https://git.kernel.org/stable/c/e5b811fe793166aecc59b085c1b7c31262ef2316"}],"metrics":[{"cvssV3_1":{"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"},"scenarios":[{"lang":"en","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->slaves; 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."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-17T05:43:36.388Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.1.178"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.6.145"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.12.97"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.18.40"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"7.1.5"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-72390","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T18:48:26.249891Z"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-16T18:55:21.250Z"}}]}}}