{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2025-37913", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-04-16T04:51:23.967Z", "datePublished": "2025-05-20T15:21:44.793Z", "dateUpdated": "2026-08-05T11:58:16.487Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:58:16.487Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet_sched: qfq: Fix double list add in class with netem as child qdisc\n\nAs described in Gerrard's report [1], there are use cases where a netem\nchild qdisc will make the parent qdisc's enqueue callback reentrant.\nIn the case of qfq, there won't be a UAF, but the code will add the same\nclassifier to the list twice, which will cause memory corruption.\n\nThis patch checks whether the class was already added to the agg->active\nlist (cl_is_active) before doing the addition to cater for the reentrant\ncase.\n\n[1] https://lore.kernel.org/netdev/CAHcdcOm+03OD2j6R0=YHKqmy=VgJ8xEOKuP6c7mSgnp-TEJJbw@mail.gmail.com/" } ], "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 configuring a qfq qdisc, class, and netem child via tc/rtnetlink and then transmitting packets locally through that qdisc. Per kernel scoring guidance, tc/netlink qdisc bugs are Local.\nAC:L - The attacker fully controls every precondition — netem `duplicate 100%` makes the reentrancy deterministic, and `SO_PRIORITY` steers both the original and the cloned skb to the same qfq class, so the double list_add occurs on the first packet with no race to win.\nPR:L - The tc path is gated by `netlink_net_capable(skb, CAP_NET_ADMIN)`, which is satisfied by CAP_NET_ADMIN in the netns's owning user namespace; an unprivileged user obtains this with `unshare -Urn` (also auto-loading sch_qfq/sch_netem). This is Low, not High.\nUI:N - The attacker sets up the qdisc hierarchy and sends the packets entirely on their own; no victim action or interaction of any kind is needed.\nS:U - The corruption is confined to kernel heap structures owned by the network scheduler within the same security authority; there is no VM, IOMMU, or sandbox boundary crossed.\nC:H - The corrupted `agg->active` list retains a dangling pointer to the kfree()'d `struct qfq_class`, and `qfq_peek_skb()` reads that freed object and dereferences `cl->qdisc->ops->peek`, giving an attacker who grooms the freed slab a kernel-memory read/disclosure primitive.\nI:H - The same use-after-free yields write primitives (`cl->deficit -= len` and `list_move_tail(&cl->alist, ...)` writing two pointers into reclaimed memory) plus an indirect call through a freed function-pointer table, which is exploitable for control-flow hijack and privilege escalation.\nA:H - The double list add corrupts a doubly linked list, tripping BUG/WARN under CONFIG_DEBUG_LIST and otherwise leading to use-after-free dereferences in qfq_dequeue that oops the kernel; the trigger is repeatable at will." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/sched/sch_qfq.c" ], "versions": [ { "version": "37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea", "lessThan": "041f410aec2c1751ee22b8b73ba05d38c3a6a602", "status": "affected", "versionType": "git" }, { "version": "37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea", "lessThan": "005a479540478a820c52de098e5e767e63e36f0a", "status": "affected", "versionType": "git" }, { "version": "37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea", "lessThan": "0bf32d6fb1fcbf841bb9945570e0e2a70072c00f", "status": "affected", "versionType": "git" }, { "version": "37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea", "lessThan": "0aa23e0856b7cedb3c88d8e3d281c212c7e4fbeb", "status": "affected", "versionType": "git" }, { "version": "37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea", "lessThan": "a43783119e01849fbf2fe8855634e8989b240cb4", "status": "affected", "versionType": "git" }, { "version": "37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea", "lessThan": "53bc0b55178bd59bdd4bcd16349505cabf54b1a2", "status": "affected", "versionType": "git" }, { "version": "37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea", "lessThan": "370218e8ce711684acc4cdd3cc3c6dd7956bc165", "status": "affected", "versionType": "git" }, { "version": "37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea", "lessThan": "f139f37dcdf34b67f5bf92bc8e0f7f6b3ac63aa4", "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_qfq.c" ], "versions": [ { "version": "5.0", "status": "affected" }, { "version": "0", "lessThan": "5.0", "status": "unaffected", "versionType": "semver" }, { "version": "5.4.294", "lessThanOrEqual": "5.4.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.238", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.182", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.138", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.90", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.28", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.14.6", "lessThanOrEqual": "6.14.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.15", "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": "5.4.294" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.0", "versionEndExcluding": "5.10.238" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.0", "versionEndExcluding": "5.15.182" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.0", "versionEndExcluding": "6.1.138" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.0", "versionEndExcluding": "6.6.90" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.0", "versionEndExcluding": "6.12.28" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.0", "versionEndExcluding": "6.14.6" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.0", "versionEndExcluding": "6.15" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/041f410aec2c1751ee22b8b73ba05d38c3a6a602" }, { "url": "https://git.kernel.org/stable/c/005a479540478a820c52de098e5e767e63e36f0a" }, { "url": "https://git.kernel.org/stable/c/0bf32d6fb1fcbf841bb9945570e0e2a70072c00f" }, { "url": "https://git.kernel.org/stable/c/0aa23e0856b7cedb3c88d8e3d281c212c7e4fbeb" }, { "url": "https://git.kernel.org/stable/c/a43783119e01849fbf2fe8855634e8989b240cb4" }, { "url": "https://git.kernel.org/stable/c/53bc0b55178bd59bdd4bcd16349505cabf54b1a2" }, { "url": "https://git.kernel.org/stable/c/370218e8ce711684acc4cdd3cc3c6dd7956bc165" }, { "url": "https://git.kernel.org/stable/c/f139f37dcdf34b67f5bf92bc8e0f7f6b3ac63aa4" } ], "title": "net_sched: qfq: Fix double list add in class with netem as child qdisc", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "title": "CVE Program Container", "references": [ { "url": "https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html" }, { "url": "https://lists.debian.org/debian-lts-announce/2025/08/msg00010.html" } ], "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2025-11-03T19:57:15.106Z" } } ] } }