{
  "schemaVersion": 1,
  "attribution": [
    {
      "source": "CISA Known Exploited Vulnerabilities",
      "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog",
      "licence": "US government work"
    },
    {
      "source": "GitHub Advisory Database",
      "url": "https://github.com/advisories",
      "licence": "CC BY 4.0"
    },
    {
      "source": "Have I Been Pwned",
      "url": "https://haveibeenpwned.com/",
      "licence": "CC BY 4.0"
    },
    {
      "source": "CVE Program (CVE records)",
      "url": "https://www.cve.org/Legal/TermsOfUse",
      "licence": "CVE Terms of Use",
      "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.",
      "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy."
    },
    {
      "source": "FIRST EPSS",
      "url": "https://www.first.org/epss/",
      "licence": "free to use; FIRST requests attribution"
    }
  ],
  "record": {
    "id": "CVE-2025-39766",
    "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2025-39766",
    "idYear": 2025,
    "status": "PUBLISHED",
    "publishedAt": "2025-09-11T16:56:21.514Z",
    "updatedAt": "2026-06-11T18:44:07.476Z",
    "importedAt": "2026-10-24T01:57:34.152Z",
    "snapshot": {
      "id": "cve_2026-10-24_midnight_baseline",
      "at": "2026-10-24T00:00:00.000Z",
      "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z"
    },
    "facts": {
      "title": "net/sched: Make cake_enqueue return NET_XMIT_CN when past buffer_limit",
      "summary": "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": [
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "046f6fd5daefac7f5abdafb436b30f63bc7c602b",
              "status": "affected",
              "versionType": "git",
              "lessThan": "7689ab22de36f8db19095f6bdf11f28cfde92f5c"
            },
            {
              "version": "046f6fd5daefac7f5abdafb436b30f63bc7c602b",
              "status": "affected",
              "versionType": "git",
              "lessThan": "de04ddd2980b48caa8d7e24a7db2742917a8b280"
            },
            {
              "version": "046f6fd5daefac7f5abdafb436b30f63bc7c602b",
              "status": "affected",
              "versionType": "git",
              "lessThan": "0dacfc5372e314d1219f03e64dde3ab495a5a25e"
            },
            {
              "version": "046f6fd5daefac7f5abdafb436b30f63bc7c602b",
              "status": "affected",
              "versionType": "git",
              "lessThan": "710866fc0a64eafcb8bacd91bcb1329eb7e5035f"
            },
            {
              "version": "046f6fd5daefac7f5abdafb436b30f63bc7c602b",
              "status": "affected",
              "versionType": "git",
              "lessThan": "aa12ee1c1bd260943fd6ab556d8635811c332eeb"
            },
            {
              "version": "046f6fd5daefac7f5abdafb436b30f63bc7c602b",
              "status": "affected",
              "versionType": "git",
              "lessThan": "ff57186b2cc39766672c4c0332323933e5faaa88"
            },
            {
              "version": "046f6fd5daefac7f5abdafb436b30f63bc7c602b",
              "status": "affected",
              "versionType": "git",
              "lessThan": "62d591dde4defb1333d202410609c4ddeae060b3"
            },
            {
              "version": "046f6fd5daefac7f5abdafb436b30f63bc7c602b",
              "status": "affected",
              "versionType": "git",
              "lessThan": "15de71d06a400f7fdc15bf377a2552b0ec437cf5"
            }
          ]
        },
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "affected",
          "versions": [
            {
              "version": "4.19",
              "status": "affected"
            },
            {
              "version": "0",
              "status": "unaffected",
              "versionType": "semver",
              "lessThan": "4.19"
            },
            {
              "version": "5.4.297",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "5.4.*"
            },
            {
              "version": "5.10.241",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "5.10.*"
            },
            {
              "version": "5.15.190",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "5.15.*"
            },
            {
              "version": "6.1.149",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "6.1.*"
            },
            {
              "version": "6.6.103",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "6.6.*"
            },
            {
              "version": "6.12.44",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "6.12.*"
            },
            {
              "version": "6.16.4",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "6.16.*"
            },
            {
              "version": "6.17",
              "status": "unaffected",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ]
        }
      ]
    }
  }
}