{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2025-38193", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-04-16T04:51:23.993Z", "datePublished": "2025-07-04T13:37:17.285Z", "dateUpdated": "2026-08-05T12:00:18.140Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:00:18.140Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet_sched: sch_sfq: reject invalid perturb period\n\nGerrard Tai reported that SFQ perturb_period has no range check yet,\nand this can be used to trigger a race condition fixed in a separate patch.\n\nWe want to make sure ctl->perturb_period * HZ will not overflow\nand is positive.\n\n\ntc qd add dev lo root sfq perturb -10 # negative value : error\nError: sch_sfq: invalid perturb period.\n\ntc qd add dev lo root sfq perturb 1000000000 # too big : error\nError: sch_sfq: invalid perturb period.\n\ntc qd add dev lo root sfq perturb 2000000 # acceptable value\ntc -s -d qd sh dev lo\nqdisc sfq 8005: root refcnt 2 limit 127p quantum 64Kb depth 127 flows 128 divisor 1024 perturb 2000000sec\n Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)\n backlog 0b 0p requeues 0" } ], "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 attacker-controlled `perturb_period` arrives via an RTM_NEWQDISC netlink message on an AF_NETLINK socket (tc qdisc add/change), which requires local system access. No remote peer or packet data can influence this value.\nAC:L - A single deterministic command (`tc qdisc add dev lo root sfq perturb -10`, or a value that overflows `* HZ`) sets the malicious period every time, with no reliance on conditions outside the attacker's control; for the downstream qdisc race, this bug is itself the mechanism that makes the timing attacker-controlled and the race reliably winnable.\nPR:L - The path is gated only by `netlink_net_capable(skb, CAP_NET_ADMIN)`, evaluated against the netns owner's user namespace, so any unprivileged user obtains it with `unshare -Urn` and then configures SFQ on lo/veth. `sch_sfq` is loaded on demand via module alias, so no real root in the initial namespace is required.\nUI:N - The attacker performs the entire sequence — create the namespace, add the SFQ qdisc with the invalid period, and drive the parent qdisc change — with no action by any other user.\nS:U - The corrupted state (SFQ timer state, parent qdisc qlen/backlog accounting, and resulting freed qdisc objects) all lives within the kernel's own security authority; this is standard kernel-local escalation, not a VM, IOMMU, or hypervisor boundary crossing.\nC:H - By making the SFQ perturb timer fire at an attacker-chosen instant, this bug enables the parent-qdisc qlen/backlog underflow that yields a use-after-free of qdisc objects, giving an attacker-controllable read primitive over reclaimed kernel memory and disclosure of arbitrary kernel data.\nI:H - The same underflow-driven use-after-free permits heap spraying over the freed qdisc allocation and attacker-controlled writes into kernel structures (including function pointers in Qdisc_ops paths), which is the documented route to full privilege escalation for this class of net/sched bug.\nA:H - A negative period makes `mod_timer(jiffies + period)` expire in the past, so `sfq_perturbation()` re-arms and re-fires every tick forever, holding the root qdisc lock while rehashing every queued packet across up to 65408 flows — a permanent softirq livelock that stalls the device's transmit path, and the resulting UAF crashes the kernel outright." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/sched/sch_sfq.c" ], "versions": [ { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "e0936ff56be4e08ad5b60ec26971eae0c40af305", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "2254d038dab9c194fe6a4b1ce31034f42e91a6e5", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "956b5aebb349449b38d920d444ca1392d43719d1", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "b11a50544af691b787384089b68f740ae20a441b", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "0357da9149eac621f39e235a135ebf155f01f7c3", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "f9b97d466e6026ccbdda30bb5b71965b67ccbc82", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "590b2d7d0beadba2aa576708a05a05f0aae39295", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "7ca52541c05c832d32b112274f81a985101f9ba8", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/sched/sch_sfq.c" ], "versions": [ { "version": "2.6.12", "status": "affected" }, { "version": "0", "lessThan": "2.6.12", "status": "unaffected", "versionType": "semver" }, { "version": "5.4.297", "lessThanOrEqual": "5.4.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.240", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.186", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.142", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.95", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.35", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.15.4", "lessThanOrEqual": "6.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.16", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "5.4.297" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "5.10.240" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "5.15.186" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "6.1.142" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "6.6.95" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "6.12.35" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "6.15.4" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "6.16" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/e0936ff56be4e08ad5b60ec26971eae0c40af305" }, { "url": "https://git.kernel.org/stable/c/2254d038dab9c194fe6a4b1ce31034f42e91a6e5" }, { "url": "https://git.kernel.org/stable/c/956b5aebb349449b38d920d444ca1392d43719d1" }, { "url": "https://git.kernel.org/stable/c/b11a50544af691b787384089b68f740ae20a441b" }, { "url": "https://git.kernel.org/stable/c/0357da9149eac621f39e235a135ebf155f01f7c3" }, { "url": "https://git.kernel.org/stable/c/f9b97d466e6026ccbdda30bb5b71965b67ccbc82" }, { "url": "https://git.kernel.org/stable/c/590b2d7d0beadba2aa576708a05a05f0aae39295" }, { "url": "https://git.kernel.org/stable/c/7ca52541c05c832d32b112274f81a985101f9ba8" } ], "title": "net_sched: sch_sfq: reject invalid perturb period", "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": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2025-11-03T17:35:17.196Z" } } ] } }