{"dataType": "CVE_RECORD", "dataVersion": "5.1", "cveMetadata": {"cveId": "CVE-2025-39766", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-04-16T07:20:57.126Z", "datePublished": "2025-09-11T16:56:21.514Z", "dateUpdated": "2025-09-11T16:56:21.514Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2025-09-11T16:56:21.514Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: Make cake_enqueue return NET_XMIT_CN when past buffer_limit\n\nThe following setup can trigger a WARNING in htb_activate due to\nthe condition: !cl->leaf.q->q.qlen\n\ntc qdisc del dev lo root\ntc qdisc add dev lo root handle 1: htb default 1\ntc class add dev lo parent 1: classid 1:1 \\\n htb rate 64bit\ntc qdisc add dev lo parent 1:1 handle f: \\\n cake memlimit 1b\nping -I lo -f -c1 -s64 -W0.001 127.0.0.1\n\nThis is because the low memlimit leads to a low buffer_limit, which\ncauses packet dropping. However, cake_enqueue still returns\nNET_XMIT_SUCCESS, causing htb_enqueue to call htb_activate with an\nempty child qdisc. We should return NET_XMIT_CN when packets are\ndropped from the same tin and flow.\n\nI do not believe return value of NET_XMIT_CN is necessary for packet\ndrops in the case of ack filtering, as that is meant to optimize\nperformance, not to signal congestion."}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/sched/sch_cake.c"], "versions": [{"version": "046f6fd5daefac7f5abdafb436b30f63bc7c602b", "lessThan": "7689ab22de36f8db19095f6bdf11f28cfde92f5c", "status": "affected", "versionType": "git"}, {"version": "046f6fd5daefac7f5abdafb436b30f63bc7c602b", "lessThan": "de04ddd2980b48caa8d7e24a7db2742917a8b280", "status": "affected", "versionType": "git"}, {"version": "046f6fd5daefac7f5abdafb436b30f63bc7c602b", "lessThan": "0dacfc5372e314d1219f03e64dde3ab495a5a25e", "status": "affected", "versionType": "git"}, {"version": "046f6fd5daefac7f5abdafb436b30f63bc7c602b", "lessThan": "710866fc0a64eafcb8bacd91bcb1329eb7e5035f", "status": "affected", "versionType": "git"}, {"version": "046f6fd5daefac7f5abdafb436b30f63bc7c602b", "lessThan": "aa12ee1c1bd260943fd6ab556d8635811c332eeb", "status": "affected", "versionType": "git"}, {"version": "046f6fd5daefac7f5abdafb436b30f63bc7c602b", "lessThan": "ff57186b2cc39766672c4c0332323933e5faaa88", "status": "affected", "versionType": "git"}, {"version": "046f6fd5daefac7f5abdafb436b30f63bc7c602b", "lessThan": "62d591dde4defb1333d202410609c4ddeae060b3", "status": "affected", "versionType": "git"}, {"version": "046f6fd5daefac7f5abdafb436b30f63bc7c602b", "lessThan": "15de71d06a400f7fdc15bf377a2552b0ec437cf5", "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_cake.c"], "versions": [{"version": "4.19", "status": "affected"}, {"version": "0", "lessThan": "4.19", "status": "unaffected", "versionType": "semver"}, {"version": "5.4.297", "lessThanOrEqual": "5.4.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.10.241", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.15.190", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.1.149", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.103", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.44", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.16.4", "lessThanOrEqual": "6.16.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.17-rc3", "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": "4.19", "versionEndExcluding": "5.4.297"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.19", "versionEndExcluding": "5.10.241"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.19", "versionEndExcluding": "5.15.190"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.19", "versionEndExcluding": "6.1.149"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.19", "versionEndExcluding": "6.6.103"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.19", "versionEndExcluding": "6.12.44"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.19", "versionEndExcluding": "6.16.4"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.19", "versionEndExcluding": "6.17-rc3"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/7689ab22de36f8db19095f6bdf11f28cfde92f5c"}, {"url": "https://git.kernel.org/stable/c/de04ddd2980b48caa8d7e24a7db2742917a8b280"}, {"url": "https://git.kernel.org/stable/c/0dacfc5372e314d1219f03e64dde3ab495a5a25e"}, {"url": "https://git.kernel.org/stable/c/710866fc0a64eafcb8bacd91bcb1329eb7e5035f"}, {"url": "https://git.kernel.org/stable/c/aa12ee1c1bd260943fd6ab556d8635811c332eeb"}, {"url": "https://git.kernel.org/stable/c/ff57186b2cc39766672c4c0332323933e5faaa88"}, {"url": "https://git.kernel.org/stable/c/62d591dde4defb1333d202410609c4ddeae060b3"}, {"url": "https://git.kernel.org/stable/c/15de71d06a400f7fdc15bf377a2552b0ec437cf5"}], "title": "net/sched: Make cake_enqueue return NET_XMIT_CN when past buffer_limit", "x_generator": {"engine": "bippy-1.2.0"}}}}

{}

{"cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: Make cake_enqueue return NET_XMIT_CN when past buffer_limit\n\nThe following setup can trigger a WARNING in htb_activate due to\nthe condition: !cl->leaf.q->q.qlen\n\ntc qdisc del dev lo root\ntc qdisc add dev lo root handle 1: htb default 1\ntc class add dev lo parent 1: classid 1:1 \\\n htb rate 64bit\ntc qdisc add dev lo parent 1:1 handle f: \\\n cake memlimit 1b\nping -I lo -f -c1 -s64 -W0.001 127.0.0.1\n\nThis is because the low memlimit leads to a low buffer_limit, which\ncauses packet dropping. However, cake_enqueue still returns\nNET_XMIT_SUCCESS, causing htb_enqueue to call htb_activate with an\nempty child qdisc. We should return NET_XMIT_CN when packets are\ndropped from the same tin and flow.\n\nI do not believe return value of NET_XMIT_CN is necessary for packet\ndrops in the case of ack filtering, as that is meant to optimize\nperformance, not to signal congestion."}], "id": "CVE-2025-39766", "lastModified": "2025-09-11T17:15:41.623", "metrics": {}, "published": "2025-09-11T17:15:41.623", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/0dacfc5372e314d1219f03e64dde3ab495a5a25e"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/15de71d06a400f7fdc15bf377a2552b0ec437cf5"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/62d591dde4defb1333d202410609c4ddeae060b3"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/710866fc0a64eafcb8bacd91bcb1329eb7e5035f"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/7689ab22de36f8db19095f6bdf11f28cfde92f5c"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/aa12ee1c1bd260943fd6ab556d8635811c332eeb"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/de04ddd2980b48caa8d7e24a7db2742917a8b280"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/ff57186b2cc39766672c4c0332323933e5faaa88"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{"bugzilla": {"description": "kernel: net/sched: Make cake_enqueue return NET_XMIT_CN when past buffer_limit", "id": "2394648", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2394648"}, "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"}, "details": ["No description is available for this CVE."], "name": "CVE-2025-39766", "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": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "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": "2025-09-11T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2025-39766\nhttps://nvd.nist.gov/vuln/detail/CVE-2025-39766\nhttps://lore.kernel.org/linux-cve-announce/2025091144-CVE-2025-39766-7465@gregkh/T"], "threat_severity": "Moderate"}