{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2025-37890", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-04-16T04:51:23.963Z", "datePublished": "2025-05-16T13:01:12.798Z", "dateUpdated": "2026-08-05T11:58:05.817Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:58:05.817Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet_sched: hfsc: Fix a UAF vulnerability in class with netem as child qdisc\n\nAs described in Gerrard's report [1], we have a UAF case when an hfsc class\nhas a netem child qdisc. The crux of the issue is that hfsc is assuming\nthat checking for cl->qdisc->q.qlen == 0 guarantees that it hasn't inserted\nthe class in the vttree or eltree (which is not true for the netem\nduplicate case).\n\nThis patch checks the n_active class variable to make sure that the code\nwon't insert the class in the vttree or eltree twice, catering for the\nreentrant case.\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 an hfsc qdisc with a netem child (duplicate enabled) via RTNETLINK/tc and then transmitting packets locally, so the attacker must have local access to the system. Per kernel scoring guidance, tc/netlink qdisc bugs are Local.\nAC:L - The reentrancy is deterministic — netem's duplicate path re-enters hfsc_enqueue() synchronously on the same CPU before the child qdisc's qlen is incremented, so a single packet with duplicate=100% reliably double-activates the class. No race or uncontrolled memory-layout condition is involved.\nPR:L - Qdisc/class creation requires CAP_NET_ADMIN, but only ns_capable() over the netns owner user namespace (netlink_net_capable in rtnetlink_rcv_msg), which any unprivileged user obtains with `unshare -Urn` on default distro configs. Triggering enqueue only needs sending a packet over the local device.\nUI:N - The attacker performs every step — qdisc/class setup, packet transmission, and class deletion — with no action from any other user or administrator.\nS:U - The corruption and its consequences are confined to the kernel's own memory and scheduling structures within the same security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - The freed hfsc_class remains linked in the parent's vt_tree/cf_tree and the eligible rbtree, so subsequent rbtree traversals read attacker-groomed heap contents; a UAF of a slab object with reclaimed contents yields a kernel information-disclosure primitive.\nI:H - Stale rb_node links cause rb_insert_color()/rb_erase()/vttree_update() to write into freed memory that the attacker can reclaim with a controlled object, giving a write primitive suitable for control-flow hijacking and privilege escalation. The doubly-inserted el_node additionally corrupts the eligible rbtree structure itself.\nA:H - Even without weaponization, the use-after-free and corrupted rbtree produce oopses, hangs on cyclic tree traversal, or a kernel panic, taking the whole system down." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/sched/sch_hfsc.c" ], "versions": [ { "version": "37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea", "lessThan": "273bbcfa53541cde38b2003ad88a59b770306421", "status": "affected", "versionType": "git" }, { "version": "37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea", "lessThan": "e0cf8ee23e1915431f262a7b2dee0c7a7d699af0", "status": "affected", "versionType": "git" }, { "version": "37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea", "lessThan": "e3e949a39a91d1f829a4890e7dfe9417ac72e4d0", "status": "affected", "versionType": "git" }, { "version": "37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea", "lessThan": "8df7d37d626430035b413b97cee18396b3450bef", "status": "affected", "versionType": "git" }, { "version": "37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea", "lessThan": "6082a87af4c52f58150d40dec1716011d871ac21", "status": "affected", "versionType": "git" }, { "version": "37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea", "lessThan": "2e7093c7a8aba5d4f8809f271488e5babe75e202", "status": "affected", "versionType": "git" }, { "version": "37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea", "lessThan": "ac39fd4a757584d78ed062d4f6fd913f83bd98b5", "status": "affected", "versionType": "git" }, { "version": "37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea", "lessThan": "141d34391abbb315d68556b7c67ad97885407547", "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_hfsc.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/273bbcfa53541cde38b2003ad88a59b770306421" }, { "url": "https://git.kernel.org/stable/c/e0cf8ee23e1915431f262a7b2dee0c7a7d699af0" }, { "url": "https://git.kernel.org/stable/c/e3e949a39a91d1f829a4890e7dfe9417ac72e4d0" }, { "url": "https://git.kernel.org/stable/c/8df7d37d626430035b413b97cee18396b3450bef" }, { "url": "https://git.kernel.org/stable/c/6082a87af4c52f58150d40dec1716011d871ac21" }, { "url": "https://git.kernel.org/stable/c/2e7093c7a8aba5d4f8809f271488e5babe75e202" }, { "url": "https://git.kernel.org/stable/c/ac39fd4a757584d78ed062d4f6fd913f83bd98b5" }, { "url": "https://git.kernel.org/stable/c/141d34391abbb315d68556b7c67ad97885407547" } ], "title": "net_sched: hfsc: Fix a UAF vulnerability 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": "2025-11-03T19:57:02.260Z" } }, { "metrics": [ { "other": { "type": "ssvc", "content": { "id": "CVE-2025-37890", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "total" } ], "version": "2.0.3", "timestamp": "2026-06-10T20:42:08.844756Z" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-06-11T18:44:19.853Z" } } ] } }