{"id":"CVE-2025-38107","state":"PUBLISHED","title":"net_sched: ets: fix a race in ets_qdisc_change()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet_sched: ets: fix a race in ets_qdisc_change()\n\nGerrard Tai reported a race condition in ETS, whenever SFQ perturb timer\nfires at the wrong time.\n\nThe race is as follows:\n\nCPU 0                                 CPU 1\n[1]: lock root\n[2]: qdisc_tree_flush_backlog()\n[3]: unlock root\n |\n |                                    [5]: lock root\n |                                    [6]: rehash\n |                                    [7]: qdisc_tree_reduce_backlog()\n |\n[4]: qdisc_put()\n\nThis can be abused to underflow a parent's qlen.\n\nCalling qdisc_purge_queue() instead of qdisc_tree_flush_backlog()\nshould fix the race, because all packets will be purged from the qdisc\nbefore releasing the lock.","publishedAt":"2025-07-03T08:35:17.487Z","updatedAt":"2026-10-15T21:52:08.363Z","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":"699d82e9a6db29d509a71f1f2f4316231e6232e6","status":"affected","lessThan":"eb7b74e9754e1ba2088f914ad1f57a778b11894b","versionType":"git"},{"version":"ce881ddbdc028fb1988b66e40e45ca0529c23b46","status":"affected","lessThan":"0b479d0aa488cb478eb2e1d8868be946ac8afb4f","versionType":"git"},{"version":"b05972f01e7d30419987a1f221b5593668fd6448","status":"affected","lessThan":"347867cb424edae5fec1622712c8dd0a2c42918f","versionType":"git"},{"version":"b05972f01e7d30419987a1f221b5593668fd6448","status":"affected","lessThan":"0383b25488a545be168744336847549d4a2d3d6c","versionType":"git"},{"version":"b05972f01e7d30419987a1f221b5593668fd6448","status":"affected","lessThan":"073f64c03516bcfaf790f8edc772e0cfb8a84ec3","versionType":"git"},{"version":"b05972f01e7d30419987a1f221b5593668fd6448","status":"affected","lessThan":"fed94bd51d62d2e0e006aa61480e94e5cd0582b0","versionType":"git"},{"version":"b05972f01e7d30419987a1f221b5593668fd6448","status":"affected","lessThan":"d92adacdd8c2960be856e0b82acc5b7c5395fddb","versionType":"git"},{"version":"fffa19b5e58c34004a0d6f642d9c24b11d213994","status":"affected","versionType":"git"},{"version":"fb155f6597cd7bc3aeed668c3bb15fc3b7cb257d","status":"affected","versionType":"git"},{"version":"5.10.142","status":"affected","lessThan":"5.10.239","versionType":"semver"},{"version":"5.15.66","status":"affected","lessThan":"5.15.186","versionType":"semver"},{"version":"5.4.213","status":"affected","lessThan":"5.5","versionType":"semver"},{"version":"5.19.8","status":"affected","lessThan":"5.20","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sched/sch_ets.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.0","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.0","versionType":"semver"},{"version":"5.10.239","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.186","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.142","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.94","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.34","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.15.3","status":"unaffected","lessThanOrEqual":"6.15.*","versionType":"semver"},{"version":"6.16","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_ets.c"]}],"references":["https://git.kernel.org/stable/c/eb7b74e9754e1ba2088f914ad1f57a778b11894b","https://git.kernel.org/stable/c/0b479d0aa488cb478eb2e1d8868be946ac8afb4f","https://git.kernel.org/stable/c/347867cb424edae5fec1622712c8dd0a2c42918f","https://git.kernel.org/stable/c/0383b25488a545be168744336847549d4a2d3d6c","https://git.kernel.org/stable/c/073f64c03516bcfaf790f8edc772e0cfb8a84ec3","https://git.kernel.org/stable/c/fed94bd51d62d2e0e006aa61480e94e5cd0582b0","https://git.kernel.org/stable/c/d92adacdd8c2960be856e0b82acc5b7c5395fddb","https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html","https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html"],"weaknesses":[],"ingestedAt":"2026-10-29T20:09:09.358Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2025/38xxx/CVE-2025-38107.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-38107","state":"PUBLISHED","datePublished":"2025-07-03T08:35:17.487Z","dateUpdated":"2026-10-15T21:52:08.363Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2025-04-16T04:51:23.985Z"},"containers":{"cna":{"title":"net_sched: ets: fix a race in ets_qdisc_change()","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet_sched: ets: fix a race in ets_qdisc_change()\n\nGerrard Tai reported a race condition in ETS, whenever SFQ perturb timer\nfires at the wrong time.\n\nThe race is as follows:\n\nCPU 0                                 CPU 1\n[1]: lock root\n[2]: qdisc_tree_flush_backlog()\n[3]: unlock root\n |\n |                                    [5]: lock root\n |                                    [6]: rehash\n |                                    [7]: qdisc_tree_reduce_backlog()\n |\n[4]: qdisc_put()\n\nThis can be abused to underflow a parent's qlen.\n\nCalling qdisc_purge_queue() instead of qdisc_tree_flush_backlog()\nshould fix the race, because all packets will be purged from the qdisc\nbefore releasing the lock."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"699d82e9a6db29d509a71f1f2f4316231e6232e6","status":"affected","lessThan":"eb7b74e9754e1ba2088f914ad1f57a778b11894b","versionType":"git"},{"version":"ce881ddbdc028fb1988b66e40e45ca0529c23b46","status":"affected","lessThan":"0b479d0aa488cb478eb2e1d8868be946ac8afb4f","versionType":"git"},{"version":"b05972f01e7d30419987a1f221b5593668fd6448","status":"affected","lessThan":"347867cb424edae5fec1622712c8dd0a2c42918f","versionType":"git"},{"version":"b05972f01e7d30419987a1f221b5593668fd6448","status":"affected","lessThan":"0383b25488a545be168744336847549d4a2d3d6c","versionType":"git"},{"version":"b05972f01e7d30419987a1f221b5593668fd6448","status":"affected","lessThan":"073f64c03516bcfaf790f8edc772e0cfb8a84ec3","versionType":"git"},{"version":"b05972f01e7d30419987a1f221b5593668fd6448","status":"affected","lessThan":"fed94bd51d62d2e0e006aa61480e94e5cd0582b0","versionType":"git"},{"version":"b05972f01e7d30419987a1f221b5593668fd6448","status":"affected","lessThan":"d92adacdd8c2960be856e0b82acc5b7c5395fddb","versionType":"git"},{"version":"fffa19b5e58c34004a0d6f642d9c24b11d213994","status":"affected","versionType":"git"},{"version":"fb155f6597cd7bc3aeed668c3bb15fc3b7cb257d","status":"affected","versionType":"git"},{"version":"5.10.142","status":"affected","lessThan":"5.10.239","versionType":"semver"},{"version":"5.15.66","status":"affected","lessThan":"5.15.186","versionType":"semver"},{"version":"5.4.213","status":"affected","lessThan":"5.5","versionType":"semver"},{"version":"5.19.8","status":"affected","lessThan":"5.20","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sched/sch_ets.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.0","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.0","versionType":"semver"},{"version":"5.10.239","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.186","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.142","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.94","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.34","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.15.3","status":"unaffected","lessThanOrEqual":"6.15.*","versionType":"semver"},{"version":"6.16","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_ets.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/eb7b74e9754e1ba2088f914ad1f57a778b11894b"},{"url":"https://git.kernel.org/stable/c/0b479d0aa488cb478eb2e1d8868be946ac8afb4f"},{"url":"https://git.kernel.org/stable/c/347867cb424edae5fec1622712c8dd0a2c42918f"},{"url":"https://git.kernel.org/stable/c/0383b25488a545be168744336847549d4a2d3d6c"},{"url":"https://git.kernel.org/stable/c/073f64c03516bcfaf790f8edc772e0cfb8a84ec3"},{"url":"https://git.kernel.org/stable/c/fed94bd51d62d2e0e006aa61480e94e5cd0582b0"},{"url":"https://git.kernel.org/stable/c/d92adacdd8c2960be856e0b82acc5b7c5395fddb"}],"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 - The vulnerable code is reached only through `RTM_NEWQDISC` netlink messages (`tc qdisc change ... ets bands N`) plus locally enqueued packets, requiring local system access. No remote peer input reaches `ets_qdisc_change()`.\nAC:L - The attacker controls both sides of the race — they configure the SFQ child's `perturb` period, choose when to issue the band-shrinking `tc` change, and can retry the sequence unboundedly until the timer lands in the unlocked window between `sch_tree_unlock()` and `qdisc_put()`.\nPR:L - The tc/qdisc netlink path is gated only by `netlink_net_capable(skb, CAP_NET_ADMIN)` against the netns' own user namespace, so an unprivileged user obtains it via `unshare -Urn` and can also autoload `sch_ets`/`sch_sfq` from that context.\nUI:N - The attacker performs every step — creating the qdisc hierarchy, generating traffic, and triggering the change — entirely on their own. No victim action is involved.\nS:U - The corrupted `qlen`/`backlog` accounting and any resulting memory corruption are confined to the kernel's own security authority; this is standard local kernel privilege escalation with no VM, IOMMU, or sandbox boundary crossed.\nC:H - The double-subtraction underflows an unsigned `q.qlen`, desynchronizing the qdisc tree so classes remain on active lists after their child qdiscs are freed, yielding a use-after-free on `struct Qdisc`/class objects that can be groomed into an arbitrary kernel-memory read.\nI:H - The same qlen-desync-to-UAF primitive gives control over reallocated heap objects and their function pointers/list heads, enabling arbitrary write and control-flow hijacking — the well-known net/sched local privilege escalation pattern.\nA:H - Even unweaponized, the underflowed `qlen` makes an empty qdisc appear to hold ~4 billion packets, causing dequeue-from-empty warnings, stuck transmit paths, and use-after-free oopses that panic the kernel."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T11:59:35.210Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10.142","versionEndExcluding":"5.10.239"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15.66","versionEndExcluding":"5.15.186"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.0","versionEndExcluding":"6.1.142"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.0","versionEndExcluding":"6.6.94"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.0","versionEndExcluding":"6.12.34"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.0","versionEndExcluding":"6.15.3"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.0","versionEndExcluding":"6.16"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.4.213"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.19.8"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CVE Program Container","references":[{"url":"https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html"},{"url":"https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html"}],"providerMetadata":{"shortName":"CVE","orgId":"af854a3a-2127-422b-91ae-364da2661108","dateUpdated":"2025-11-03T17:34:09.673Z"}},{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2025-38107","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-15T21:47:26.074069Z"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-15T21:52:08.363Z"}}]}}}