CVE-2025-37797

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The issue occurs due to a time-of-check/time-of-use condition\nin hfsc_change_class() when working with certain child qdiscs like netem\nor codel.\n\nThe vulnerability works as follows:\n1. hfsc_change_class() checks if a class has packets (q.qlen != 0)\n2. It then calls qdisc_peek_len(), which for certain qdiscs (e.g.,\n codel, netem) might drop packets and empty the queue\n3. The code continues assuming the queue is still non-empty, adding\n the class to vttree\n4. This breaks HFSC scheduler assumptions that only non-empty classes\n are in vttree\n5. Later, when the class is destroyed, this can lead to a Use-After-Free\n\nThe fix adds a second queue length check after qdisc_peek_len() to verify\nthe queue wasn't emptied."}], "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 entire attack sequence (create hfsc qdisc, attach a codel/netem child, `tc class change`, then `tc class del`) is driven through rtnetlink RTM_NEWTCLASS/RTM_DELTCLASS messages, which require local system access. Per kernel CNA guidance, tc/netlink qdisc bugs are Local.\nAC:L - This is a deterministic time-of-check/time-of-use flaw inside a single netlink operation, not a thread race \u2014 the attacker picks the child qdisc (codel/netem) and its parameters so the peek is guaranteed to drop the packet and empty the queue. No condition outside the attacker's control is involved, and a reliable reproducer existed.\nPR:L - The tc class paths only check `netlink_ns_capable(skb, net->user_ns, CAP_NET_ADMIN)`, which an unprivileged user satisfies inside a new user+net namespace (`unshare -Urn`), where they can create a dummy/veth device, build the hfsc hierarchy and generate the traffic. Per guidance, tc/qdisc reachable via user namespaces is Low, not High.\nUI:N - The attacker performs every step \u2014 qdisc/class configuration, packet generation, class change and class deletion \u2014 with no action by any other user. Subsequent dequeue on the attacker's own device triggers the freed-object access.\nS:U - The corruption and its consequences are confined to the kernel's own memory and privilege domain; there is no crossing of a VM, IOMMU, or other security-authority boundary. Standard kernel-local privilege escalation is Unchanged.\nC:H - The freed `hfsc_class` remains linked in the parent's vt_tree/eltree, so `vttree_firstfit()`/`eltree_get_mindl()` read `cl_f`, `cl_vt`, `cl_parent` and `cl->qdisc` out of reclaimed slab memory, giving an attacker who sprays the slot a controlled read primitive and kernel memory disclosure.\nI:H - The dangling rb_node yields `rb_erase()`/`rb_insert_color()` pointer writes plus the direct `cl->cl_parent->cl_cvtmin = cl->cl_vt` write through freed memory, and `qdisc_dequeue_peeked()` makes an indirect call through `cl->qdisc->ops->dequeue` read from the freed object \u2014 a full write/control-flow-hijack primitive for privilege escalation.\nA:H - Even without successful exploitation, traversing and erasing rb-tree nodes inside a kfree()d `hfsc_class` reliably corrupts the scheduler tree and panics or oopses the kernel, and the attacker can repeat it at will."}]}], "affected": [{"product": "Linux", "vendor": "Linux", 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"21f4d5cc25ec0e6e8eb8420dd2c399e6d2fc7d14", "lessThan": "86cd4641c713455a4f1c8e54c370c598c2b1cee0", "status": "affected", "versionType": "git"}, {"version": "21f4d5cc25ec0e6e8eb8420dd2c399e6d2fc7d14", "lessThan": "bb583c88d23b72d8d16453d24856c99bd93dadf5", "status": "affected", "versionType": "git"}, {"version": "21f4d5cc25ec0e6e8eb8420dd2c399e6d2fc7d14", "lessThan": "3df275ef0a6ae181e8428a6589ef5d5231e58b5c", "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": "4.14", "status": "affected"}, {"version": "0", "lessThan": "4.14", "status": "unaffected", "versionType": "semver"}, {"version": "5.4.293", "lessThanOrEqual": "5.4.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.10.237", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.15.181", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.1.136", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.89", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.26", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.14.5", "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": "4.14", "versionEndExcluding": "5.4.293"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.14", "versionEndExcluding": "5.10.237"}, 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{"url": "https://git.kernel.org/stable/c/39b9095dd3b55d9b2743df038c32138efa34a9de"}, {"url": "https://git.kernel.org/stable/c/fcc8ede663569c704fb00a702973bd6c00373283"}, {"url": "https://git.kernel.org/stable/c/20d584a33e480ae80d105f43e0e7b56784da41b9"}, {"url": "https://git.kernel.org/stable/c/3aa852e3605000d5c47035c3fc3a986d14ccfa9f"}, {"url": "https://git.kernel.org/stable/c/86cd4641c713455a4f1c8e54c370c598c2b1cee0"}, {"url": "https://git.kernel.org/stable/c/bb583c88d23b72d8d16453d24856c99bd93dadf5"}, {"url": "https://git.kernel.org/stable/c/3df275ef0a6ae181e8428a6589ef5d5231e58b5c"}], "title": "net_sched: hfsc: Fix a UAF vulnerability in class handling", "x_generator": {"engine": "bippy-1.2.0"}}, "adp": [{"title": "CVE Program Container", "references": [{"url": "https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html"}, {"url": "https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html"}], "providerMetadata": {"orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2025-11-03T19:55:28.428Z"}}, {"metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2025-37797", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "total"}], "version": "2.0.3", "timestamp": "2026-06-10T20:40:32.363946Z"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-06-11T18:44:02.667Z"}}]}}

{"dataType": "CVE_RECORD", "containers": {"adp": [{"title": "CVE Program Container", "references": [{"url": "https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html"}, {"url": "https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html"}], "providerMetadata": {"orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2025-11-03T19:55:28.428Z"}}, {"title": "CISA ADP Vulnrichment", "metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2025-37797", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "total"}], "version": "2.0.3", "timestamp": "2026-06-10T20:40:32.363946Z"}}}], "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-06-11T17:37:24.801Z"}}], "cna": {"title": "net_sched: hfsc: Fix a UAF vulnerability in class handling", "metrics": [{"cvssV3_1": {"version": "3.1", "baseScore": 7.8, "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}, "scenarios": [{"lang": "en", "value": "AV:L - The entire attack sequence (create hfsc qdisc, attach a codel/netem child, `tc class change`, then `tc class del`) is driven through rtnetlink RTM_NEWTCLASS/RTM_DELTCLASS messages, which require local system access. Per kernel CNA guidance, tc/netlink qdisc bugs are Local.\nAC:L - This is a deterministic time-of-check/time-of-use flaw inside a single netlink operation, not a thread race \u2014 the attacker picks the child qdisc (codel/netem) and its parameters so the peek is guaranteed to drop the packet and empty the queue. No condition outside the attacker's control is involved, and a reliable reproducer existed.\nPR:L - The tc class paths only check `netlink_ns_capable(skb, net->user_ns, CAP_NET_ADMIN)`, which an unprivileged user satisfies inside a new user+net namespace (`unshare -Urn`), where they can create a dummy/veth device, build the hfsc hierarchy and generate the traffic. Per guidance, tc/qdisc reachable via user namespaces is Low, not High.\nUI:N - The attacker performs every step \u2014 qdisc/class configuration, packet generation, class change and class deletion \u2014 with no action by any other user. Subsequent dequeue on the attacker's own device triggers the freed-object access.\nS:U - The corruption and its consequences are confined to the kernel's own memory and privilege domain; there is no crossing of a VM, IOMMU, or other security-authority boundary. Standard kernel-local privilege escalation is Unchanged.\nC:H - The freed `hfsc_class` remains linked in the parent's vt_tree/eltree, so `vttree_firstfit()`/`eltree_get_mindl()` read `cl_f`, `cl_vt`, `cl_parent` and `cl->qdisc` out of reclaimed slab memory, giving an attacker who sprays the slot a controlled read primitive and kernel memory disclosure.\nI:H - The dangling rb_node yields `rb_erase()`/`rb_insert_color()` pointer writes plus the direct `cl->cl_parent->cl_cvtmin = cl->cl_vt` write through freed memory, and `qdisc_dequeue_peeked()` makes an indirect call through `cl->qdisc->ops->dequeue` read from the freed object \u2014 a full write/control-flow-hijack primitive for privilege escalation.\nA:H - Even without successful exploitation, traversing and erasing rb-tree nodes inside a kfree()d `hfsc_class` reliably corrupts the scheduler tree and panics or oopses the kernel, and the attacker can repeat it at will."}]}], "affected": [{"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "product": "Linux", "versions": [{"status": "affected", "version": "21f4d5cc25ec0e6e8eb8420dd2c399e6d2fc7d14", "lessThan": "28b09a067831f7317c3841812276022d6c940677", "versionType": "git"}, {"status": "affected", "version": "21f4d5cc25ec0e6e8eb8420dd2c399e6d2fc7d14", "lessThan": "39b9095dd3b55d9b2743df038c32138efa34a9de", "versionType": "git"}, {"status": "affected", "version": "21f4d5cc25ec0e6e8eb8420dd2c399e6d2fc7d14", "lessThan": "fcc8ede663569c704fb00a702973bd6c00373283", "versionType": "git"}, {"status": "affected", "version": "21f4d5cc25ec0e6e8eb8420dd2c399e6d2fc7d14", "lessThan": "20d584a33e480ae80d105f43e0e7b56784da41b9", "versionType": "git"}, {"status": "affected", "version": "21f4d5cc25ec0e6e8eb8420dd2c399e6d2fc7d14", "lessThan": "3aa852e3605000d5c47035c3fc3a986d14ccfa9f", "versionType": "git"}, {"status": "affected", "version": "21f4d5cc25ec0e6e8eb8420dd2c399e6d2fc7d14", "lessThan": "86cd4641c713455a4f1c8e54c370c598c2b1cee0", "versionType": "git"}, {"status": "affected", "version": "21f4d5cc25ec0e6e8eb8420dd2c399e6d2fc7d14", "lessThan": "bb583c88d23b72d8d16453d24856c99bd93dadf5", "versionType": "git"}, {"status": "affected", "version": "21f4d5cc25ec0e6e8eb8420dd2c399e6d2fc7d14", "lessThan": "3df275ef0a6ae181e8428a6589ef5d5231e58b5c", "versionType": "git"}], "programFiles": ["net/sched/sch_hfsc.c"], "defaultStatus": "unaffected"}, {"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "product": "Linux", "versions": [{"status": "affected", "version": "4.14"}, {"status": "unaffected", "version": "0", "lessThan": "4.14", "versionType": "semver"}, {"status": "unaffected", "version": "5.4.293", "versionType": "semver", "lessThanOrEqual": "5.4.*"}, {"status": "unaffected", "version": "5.10.237", "versionType": "semver", "lessThanOrEqual": "5.10.*"}, {"status": "unaffected", "version": "5.15.181", "versionType": "semver", "lessThanOrEqual": "5.15.*"}, {"status": "unaffected", "version": "6.1.136", "versionType": "semver", "lessThanOrEqual": "6.1.*"}, {"status": "unaffected", "version": "6.6.89", "versionType": "semver", "lessThanOrEqual": "6.6.*"}, {"status": "unaffected", "version": "6.12.26", "versionType": "semver", "lessThanOrEqual": "6.12.*"}, {"status": "unaffected", "version": "6.14.5", "versionType": "semver", "lessThanOrEqual": "6.14.*"}, {"status": "unaffected", "version": "6.15", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*"}], "programFiles": ["net/sched/sch_hfsc.c"], "defaultStatus": "affected"}], "references": [{"url": "https://git.kernel.org/stable/c/28b09a067831f7317c3841812276022d6c940677"}, {"url": "https://git.kernel.org/stable/c/39b9095dd3b55d9b2743df038c32138efa34a9de"}, {"url": "https://git.kernel.org/stable/c/fcc8ede663569c704fb00a702973bd6c00373283"}, {"url": "https://git.kernel.org/stable/c/20d584a33e480ae80d105f43e0e7b56784da41b9"}, {"url": "https://git.kernel.org/stable/c/3aa852e3605000d5c47035c3fc3a986d14ccfa9f"}, {"url": "https://git.kernel.org/stable/c/86cd4641c713455a4f1c8e54c370c598c2b1cee0"}, {"url": "https://git.kernel.org/stable/c/bb583c88d23b72d8d16453d24856c99bd93dadf5"}, {"url": "https://git.kernel.org/stable/c/3df275ef0a6ae181e8428a6589ef5d5231e58b5c"}], "x_generator": {"engine": "bippy-1.2.0"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet_sched: hfsc: Fix a UAF vulnerability in class handling\n\nThis patch fixes a Use-After-Free vulnerability in the HFSC qdisc class\nhandling. The issue occurs due to a time-of-check/time-of-use condition\nin hfsc_change_class() when working with certain child qdiscs like netem\nor codel.\n\nThe vulnerability works as follows:\n1. hfsc_change_class() checks if a class has packets (q.qlen != 0)\n2. It then calls qdisc_peek_len(), which for certain qdiscs (e.g.,\n codel, netem) might drop packets and empty the queue\n3. The code continues assuming the queue is still non-empty, adding\n the class to vttree\n4. This breaks HFSC scheduler assumptions that only non-empty classes\n are in vttree\n5. Later, when the class is destroyed, this can lead to a Use-After-Free\n\nThe fix adds a second queue length check after qdisc_peek_len() to verify\nthe queue wasn't emptied."}], "cpeApplicability": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "5.4.293", "versionStartIncluding": "4.14"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "5.10.237", "versionStartIncluding": "4.14"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "5.15.181", "versionStartIncluding": "4.14"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.1.136", "versionStartIncluding": "4.14"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.6.89", "versionStartIncluding": "4.14"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.12.26", "versionStartIncluding": "4.14"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.14.5", "versionStartIncluding": "4.14"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.15", "versionStartIncluding": "4.14"}], "operator": "OR"}]}], "providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:57:36.042Z"}}}, "cveMetadata": {"cveId": "CVE-2025-37797", "state": "PUBLISHED", "dateUpdated": "2026-08-05T11:57:36.042Z", "dateReserved": "2025-04-16T04:51:23.941Z", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "datePublished": "2025-05-02T14:16:01.905Z", "assignerShortName": "Linux"}, "dataVersion": "5.2"}

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"matchCriteriaId": "FA6FEEC2-9F11-4643-8827-749718254FED", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet_sched: hfsc: Fix a UAF vulnerability in class handling\n\nThis patch fixes a Use-After-Free vulnerability in the HFSC qdisc class\nhandling. The issue occurs due to a time-of-check/time-of-use condition\nin hfsc_change_class() when working with certain child qdiscs like netem\nor codel.\n\nThe vulnerability works as follows:\n1. hfsc_change_class() checks if a class has packets (q.qlen != 0)\n2. It then calls qdisc_peek_len(), which for certain qdiscs (e.g.,\n codel, netem) might drop packets and empty the queue\n3. The code continues assuming the queue is still non-empty, adding\n the class to vttree\n4. This breaks HFSC scheduler assumptions that only non-empty classes\n are in vttree\n5. Later, when the class is destroyed, this can lead to a Use-After-Free\n\nThe fix adds a second queue length check after qdisc_peek_len() to verify\nthe queue wasn't emptied."}, {"lang": "es", "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: net_sched: hfsc: Se corrige una vulnerabilidad de UAF en la gesti\u00f3n de clases. Este parche corrige una vulnerabilidad de use-after-free en la gesti\u00f3n de clases de qdisc HFSC. El problema se produce debido a una condici\u00f3n de tiempo de comprobaci\u00f3n/tiempo de uso en hfsc_change_class() al trabajar con ciertas qdiscs secundarias como netem o codel. La vulnerabilidad funciona de la siguiente manera: 1. hfsc_change_class() verifica si una clase tiene paquetes (q.qlen != 0) 2. Luego llama a qdisc_peek_len(), que para ciertos qdiscs (por ejemplo, codel, netem) puede descartar paquetes y vaciar la cola 3. El c\u00f3digo contin\u00faa asumiendo que la cola todav\u00eda no est\u00e1 vac\u00eda, agregando la clase a vttree 4. Esto rompe las suposiciones del programador HFSC de que solo las clases no vac\u00edas est\u00e1n en vttree 5. M\u00e1s tarde, cuando se destruye la clase, esto puede llevar a un Use-After-Free La soluci\u00f3n agrega una segunda verificaci\u00f3n de longitud de cola despu\u00e9s de qdisc_peek_len() para verificar que la cola no se haya vaciado."}], "id": "CVE-2025-37797", "lastModified": "2026-07-30T06:22:20.557", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 7.8, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 1.8, "impactScore": 5.9, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}, {"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 7.8, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 1.8, "impactScore": 5.9, "source": "nvd@nist.gov", "type": "Primary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2025-37797", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "total"}], "role": "CISA Coordinator", "timestamp": "2026-06-10T20:40:32.363946Z", "version": "2.0.3"}}]}, "published": "2025-05-02T15:15:48.557", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/20d584a33e480ae80d105f43e0e7b56784da41b9"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/28b09a067831f7317c3841812276022d6c940677"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/39b9095dd3b55d9b2743df038c32138efa34a9de"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/3aa852e3605000d5c47035c3fc3a986d14ccfa9f"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/3df275ef0a6ae181e8428a6589ef5d5231e58b5c"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/86cd4641c713455a4f1c8e54c370c598c2b1cee0"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/bb583c88d23b72d8d16453d24856c99bd93dadf5"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/fcc8ede663569c704fb00a702973bd6c00373283"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Mailing List", "Third Party Advisory"], "url": "https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Mailing List", "Third Party Advisory"], "url": "https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Modified", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-416"}], "source": "nvd@nist.gov", "type": "Primary"}]}

{"bugzilla": {"description": "kernel: net_sched: hfsc: Fix a UAF vulnerability in class handling", "id": "2363672", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2363672"}, "csaw": false, "cvss3": {"cvss3_base_score": "7.0", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H", "status": "draft"}, "cwe": "CWE-416", "details": ["In the Linux kernel, the following vulnerability has been resolved:\nnet_sched: hfsc: Fix a UAF vulnerability in class handling\nThis patch fixes a Use-After-Free vulnerability in the HFSC qdisc class\nhandling. The issue occurs due to a time-of-check/time-of-use condition\nin hfsc_change_class() when working with certain child qdiscs like netem\nor codel.\nThe vulnerability works as follows:\n1. hfsc_change_class() checks if a class has packets (q.qlen != 0)\n2. It then calls qdisc_peek_len(), which for certain qdiscs (e.g.,\ncodel, netem) might drop packets and empty the queue\n3. The code continues assuming the queue is still non-empty, adding\nthe class to vttree\n4. This breaks HFSC scheduler assumptions that only non-empty classes\nare in vttree\n5. Later, when the class is destroyed, this can lead to a Use-After-Free\nThe fix adds a second queue length check after qdisc_peek_len() to verify\nthe queue wasn't emptied."], "mitigation": {"lang": "en:us", "value": "To mitigate this issue, prevent module sch_hfsc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically."}, "name": "CVE-2025-37797", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Out of support scope", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Out of support scope", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Out of support scope", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Out of support scope", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Out of support scope", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2025-05-02T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2025-37797\nhttps://nvd.nist.gov/vuln/detail/CVE-2025-37797\nhttps://lore.kernel.org/linux-cve-announce/2025050210-CVE-2025-37797-2aab@gregkh/T"], "statement": "The bug could happen only when qdisc with child qdiscs like netem or codel being used.", "threat_severity": "Moderate"}

{}