CVE-2025-39766 (GCVE-0-2025-39766)

Vulnerability from cvelistv5 – Published: 2025-09-11 16:56 – Updated: 2026-05-12 12:06
VLAI
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: net/sched: Make cake_enqueue return NET_XMIT_CN when past buffer_limit The following setup can trigger a WARNING in htb_activate due to the condition: !cl->leaf.q->q.qlen tc qdisc del dev lo root tc qdisc add dev lo root handle 1: htb default 1 tc class add dev lo parent 1: classid 1:1 \ htb rate 64bit tc qdisc add dev lo parent 1:1 handle f: \ cake memlimit 1b ping -I lo -f -c1 -s64 -W0.001 127.0.0.1 This is because the low memlimit leads to a low buffer_limit, which causes packet dropping. However, cake_enqueue still returns NET_XMIT_SUCCESS, causing htb_enqueue to call htb_activate with an empty child qdisc. We should return NET_XMIT_CN when packets are dropped from the same tin and flow. I do not believe return value of NET_XMIT_CN is necessary for packet drops in the case of ack filtering, as that is meant to optimize performance, not to signal congestion.
Severity
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 046f6fd5daefac7f5abdafb436b30f63bc7c602b , < 7689ab22de36f8db19095f6bdf11f28cfde92f5c (git)
Affected: 046f6fd5daefac7f5abdafb436b30f63bc7c602b , < de04ddd2980b48caa8d7e24a7db2742917a8b280 (git)
Affected: 046f6fd5daefac7f5abdafb436b30f63bc7c602b , < 0dacfc5372e314d1219f03e64dde3ab495a5a25e (git)
Affected: 046f6fd5daefac7f5abdafb436b30f63bc7c602b , < 710866fc0a64eafcb8bacd91bcb1329eb7e5035f (git)
Affected: 046f6fd5daefac7f5abdafb436b30f63bc7c602b , < aa12ee1c1bd260943fd6ab556d8635811c332eeb (git)
Affected: 046f6fd5daefac7f5abdafb436b30f63bc7c602b , < ff57186b2cc39766672c4c0332323933e5faaa88 (git)
Affected: 046f6fd5daefac7f5abdafb436b30f63bc7c602b , < 62d591dde4defb1333d202410609c4ddeae060b3 (git)
Affected: 046f6fd5daefac7f5abdafb436b30f63bc7c602b , < 15de71d06a400f7fdc15bf377a2552b0ec437cf5 (git)
Create a notification for this product.
Linux Linux Affected: 4.19
Unaffected: 0 , < 4.19 (semver)
Unaffected: 5.4.297 , ≤ 5.4.* (semver)
Unaffected: 5.10.241 , ≤ 5.10.* (semver)
Unaffected: 5.15.190 , ≤ 5.15.* (semver)
Unaffected: 6.1.149 , ≤ 6.1.* (semver)
Unaffected: 6.6.103 , ≤ 6.6.* (semver)
Unaffected: 6.12.44 , ≤ 6.12.* (semver)
Unaffected: 6.16.4 , ≤ 6.16.* (semver)
Unaffected: 6.17 , ≤ * (original_commit_for_fix)
Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "providerMetadata": {
          "dateUpdated": "2025-11-03T17:43:11.881Z",
          "orgId": "af854a3a-2127-422b-91ae-364da2661108",
          "shortName": "CVE"
        },
        "references": [
          {
            "url": "https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html"
          },
          {
            "url": "https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html"
          }
        ],
        "title": "CVE Program Container"
      },
      {
        "affected": [
          {
            "defaultStatus": "unknown",
            "product": "SIMATIC CN 4100",
            "vendor": "Siemens",
            "versions": [
              {
                "lessThan": "V5.0",
                "status": "affected",
                "version": "0",
                "versionType": "custom"
              }
            ]
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-05-12T12:06:51.305Z",
          "orgId": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e",
          "shortName": "siemens-SADP"
        },
        "references": [
          {
            "url": "https://cert-portal.siemens.com/productcert/html/ssa-032379.html"
          }
        ],
        "x_adpType": "supplier"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/sched/sch_cake.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "7689ab22de36f8db19095f6bdf11f28cfde92f5c",
              "status": "affected",
              "version": "046f6fd5daefac7f5abdafb436b30f63bc7c602b",
              "versionType": "git"
            },
            {
              "lessThan": "de04ddd2980b48caa8d7e24a7db2742917a8b280",
              "status": "affected",
              "version": "046f6fd5daefac7f5abdafb436b30f63bc7c602b",
              "versionType": "git"
            },
            {
              "lessThan": "0dacfc5372e314d1219f03e64dde3ab495a5a25e",
              "status": "affected",
              "version": "046f6fd5daefac7f5abdafb436b30f63bc7c602b",
              "versionType": "git"
            },
            {
              "lessThan": "710866fc0a64eafcb8bacd91bcb1329eb7e5035f",
              "status": "affected",
              "version": "046f6fd5daefac7f5abdafb436b30f63bc7c602b",
              "versionType": "git"
            },
            {
              "lessThan": "aa12ee1c1bd260943fd6ab556d8635811c332eeb",
              "status": "affected",
              "version": "046f6fd5daefac7f5abdafb436b30f63bc7c602b",
              "versionType": "git"
            },
            {
              "lessThan": "ff57186b2cc39766672c4c0332323933e5faaa88",
              "status": "affected",
              "version": "046f6fd5daefac7f5abdafb436b30f63bc7c602b",
              "versionType": "git"
            },
            {
              "lessThan": "62d591dde4defb1333d202410609c4ddeae060b3",
              "status": "affected",
              "version": "046f6fd5daefac7f5abdafb436b30f63bc7c602b",
              "versionType": "git"
            },
            {
              "lessThan": "15de71d06a400f7fdc15bf377a2552b0ec437cf5",
              "status": "affected",
              "version": "046f6fd5daefac7f5abdafb436b30f63bc7c602b",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/sched/sch_cake.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.19"
            },
            {
              "lessThan": "4.19",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.4.*",
              "status": "unaffected",
              "version": "5.4.297",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.241",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.190",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.149",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.103",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.44",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.16.*",
              "status": "unaffected",
              "version": "6.16.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.17",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.4.297",
                  "versionStartIncluding": "4.19",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.10.241",
                  "versionStartIncluding": "4.19",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.15.190",
                  "versionStartIncluding": "4.19",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.149",
                  "versionStartIncluding": "4.19",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.103",
                  "versionStartIncluding": "4.19",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.44",
                  "versionStartIncluding": "4.19",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.16.4",
                  "versionStartIncluding": "4.19",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.17",
                  "versionStartIncluding": "4.19",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "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-\u003eleaf.q-\u003eq.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."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-11T21:35:50.638Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "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"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-39766",
    "datePublished": "2025-09-11T16:56:21.514Z",
    "dateReserved": "2025-04-16T07:20:57.126Z",
    "dateUpdated": "2026-05-12T12:06:51.305Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2025-39766",
      "date": "2026-05-26",
      "epss": "0.00018",
      "percentile": "0.0482"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2025-39766\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2025-09-11T17:15:41.623\",\"lastModified\":\"2026-05-12T13:17:10.073\",\"vulnStatus\":\"Modified\",\"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-\u003eleaf.q-\u003eq.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.\"}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"cvssData\":{\"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\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.8,\"impactScore\":5.9}]},\"weaknesses\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"NVD-CWE-noinfo\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"4.19\",\"versionEndExcluding\":\"5.4.297\",\"matchCriteriaId\":\"DB980BDC-B34E-41B6-BF6D-8AF3F2450143\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"5.5\",\"versionEndExcluding\":\"5.10.241\",\"matchCriteriaId\":\"D0D21C35-EB8A-488A-BBF9-403E4817E5DD\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"5.11\",\"versionEndExcluding\":\"5.15.190\",\"matchCriteriaId\":\"AD9E597F-3DDE-4D7E-976C-463D0611F13F\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"5.16\",\"versionEndExcluding\":\"6.1.149\",\"matchCriteriaId\":\"FDBE8280-8983-4D2D-943D-2E6D0104E2D8\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.2\",\"versionEndExcluding\":\"6.6.103\",\"matchCriteriaId\":\"F2293654-7169-49B5-8D0D-EE51EF8B8E48\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.7\",\"versionEndExcluding\":\"6.12.44\",\"matchCriteriaId\":\"12351F24-1133-4775-960C-F2B47E81298B\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.13\",\"versionEndExcluding\":\"6.16.4\",\"matchCriteriaId\":\"AFC28995-B8C3-4B68-8CB6-78E792B6629D\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:6.17:rc1:*:*:*:*:*:*\",\"matchCriteriaId\":\"327D22EF-390B-454C-BD31-2ED23C998A1C\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:6.17:rc2:*:*:*:*:*:*\",\"matchCriteriaId\":\"C730CD9A-D969-4A8E-9522-162AAF7C0EE9\"}]}]},{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*\",\"matchCriteriaId\":\"FA6FEEC2-9F11-4643-8827-749718254FED\"}]}]}],\"references\":[{\"url\":\"https://git.kernel.org/stable/c/0dacfc5372e314d1219f03e64dde3ab495a5a25e\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/15de71d06a400f7fdc15bf377a2552b0ec437cf5\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/62d591dde4defb1333d202410609c4ddeae060b3\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/710866fc0a64eafcb8bacd91bcb1329eb7e5035f\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/7689ab22de36f8db19095f6bdf11f28cfde92f5c\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/aa12ee1c1bd260943fd6ab556d8635811c332eeb\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/de04ddd2980b48caa8d7e24a7db2742917a8b280\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/ff57186b2cc39766672c4c0332323933e5faaa88\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\",\"tags\":[\"Mailing List\",\"Third Party Advisory\"]},{\"url\":\"https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\",\"tags\":[\"Mailing List\",\"Third Party Advisory\"]},{\"url\":\"https://cert-portal.siemens.com/productcert/html/ssa-032379.html\",\"source\":\"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e\"}]}}"
  }
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



Detection rules are retrieved from Rulezet.