{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2025-38108", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-04-16T04:51:23.985Z", "datePublished": "2025-07-03T08:35:18.523Z", "dateUpdated": "2026-08-05T11:59:36.285Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:59:36.285Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet_sched: red: fix a race in __red_change()\n\nGerrard Tai reported a race condition in RED, 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." } ], "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 path is reached only through `RTM_NEWQDISC` rtnetlink messages on a local netlink socket (`tc qdisc change ... red`), plus locally-generated traffic to fill the SFQ child. No remote peer can reach `__red_change()`.\nAC:L - The attacker controls both sides of the race — they configure the SFQ perturb period (1s), arm the timer, fill the queue so `sfq_rehash()` drops packets, and drive the `__red_change()` loop, retrying unboundedly across many RED/SFQ hierarchies with no external precondition.\nPR:L - Only CAP_NET_ADMIN within the netns owner's user namespace is required (net/core/rtnetlink.c:6922 uses `netlink_net_capable()`), which any unprivileged local user obtains via `unshare -Urn`; qdisc module autoload is not additionally gated.\nUI:N - The attacker performs every step — creating the qdisc hierarchy, generating the traffic, and issuing the change requests. No victim action is involved.\nS:U - The corrupted state and any resulting memory corruption are confined to the kernel of the same host; no VM, IOMMU, or other security-authority boundary is crossed.\nC:H - The `qlen`/`backlog` underflow desynchronizes parent qdisc accounting from its class active lists, yielding stale/freed class objects being walked in the dequeue path — a use-after-free-grade primitive that gives an attacker control over freed slab contents and thus kernel memory disclosure.\nI:H - The same qlen-underflow-to-UAF desync in classful parents (HTB/HFSC/DRR/QFQ/ETS) permits heap grooming over the freed class objects and corruption of adjacent kernel structures and function pointers, giving a write/control-flow primitive; the fix's own wording notes the underflow \"can be abused.\"\nA:H - A parent qdisc believing it holds ~4 billion packets triggers `WARN_ON`s, NULL dereferences in the dequeue path, and permanently wedged/inconsistent qdisc state, and any resulting use-after-free reliably panics the kernel." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/sched/sch_red.c" ], "versions": [ { "version": "0c8d13ac96070000da33f394f45e9c19638483c5", "lessThan": "2790c4ec481be45a80948d059cd7c9a06bc37493", "status": "affected", "versionType": "git" }, { "version": "0c8d13ac96070000da33f394f45e9c19638483c5", "lessThan": "a1bf6a4e9264a685b0e642994031f9c5aad72414", "status": "affected", "versionType": "git" }, { "version": "0c8d13ac96070000da33f394f45e9c19638483c5", "lessThan": "110a47efcf23438ff8d31dbd9c854fae2a48bf98", "status": "affected", "versionType": "git" }, { "version": "0c8d13ac96070000da33f394f45e9c19638483c5", "lessThan": "f569984417a4e12c67366e69bdcb752970de921d", "status": "affected", "versionType": "git" }, { "version": "0c8d13ac96070000da33f394f45e9c19638483c5", "lessThan": "2a71924ca4af59ffc00f0444732b6cd54b153d0e", "status": "affected", "versionType": "git" }, { "version": "0c8d13ac96070000da33f394f45e9c19638483c5", "lessThan": "4b755305b2b0618e857fdadb499365b5f2e478d1", "status": "affected", "versionType": "git" }, { "version": "0c8d13ac96070000da33f394f45e9c19638483c5", "lessThan": "444ad445df5496a785705019268a8a84b84484bb", "status": "affected", "versionType": "git" }, { "version": "0c8d13ac96070000da33f394f45e9c19638483c5", "lessThan": "85a3e0ede38450ea3053b8c45d28cf55208409b8", "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_red.c" ], "versions": [ { "version": "5.0", "status": "affected" }, { "version": "0", "lessThan": "5.0", "status": "unaffected", "versionType": "semver" }, { "version": "5.4.295", "lessThanOrEqual": "5.4.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.239", "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": "6.6.94", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.34", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.15.3", "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": "5.0", "versionEndExcluding": "5.4.295" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.0", "versionEndExcluding": "5.10.239" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.0", "versionEndExcluding": "5.15.186" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.0", "versionEndExcluding": "6.1.142" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.0", "versionEndExcluding": "6.6.94" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.0", "versionEndExcluding": "6.12.34" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.0", "versionEndExcluding": "6.15.3" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.0", "versionEndExcluding": "6.16" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/2790c4ec481be45a80948d059cd7c9a06bc37493" }, { "url": "https://git.kernel.org/stable/c/a1bf6a4e9264a685b0e642994031f9c5aad72414" }, { "url": "https://git.kernel.org/stable/c/110a47efcf23438ff8d31dbd9c854fae2a48bf98" }, { "url": "https://git.kernel.org/stable/c/f569984417a4e12c67366e69bdcb752970de921d" }, { "url": "https://git.kernel.org/stable/c/2a71924ca4af59ffc00f0444732b6cd54b153d0e" }, { "url": "https://git.kernel.org/stable/c/4b755305b2b0618e857fdadb499365b5f2e478d1" }, { "url": "https://git.kernel.org/stable/c/444ad445df5496a785705019268a8a84b84484bb" }, { "url": "https://git.kernel.org/stable/c/85a3e0ede38450ea3053b8c45d28cf55208409b8" } ], "title": "net_sched: red: fix a race in __red_change()", "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": "2025-11-03T17:34:11.552Z" } } ] } }