CVE-2021-47669 (GCVE-0-2021-47669)

Vulnerability from cvelistv5 – Published: 2025-04-17 18:01 – Updated: 2026-08-05 08:48
VLAI
Title
can: vxcan: vxcan_xmit: fix use after free bug
Summary
In the Linux kernel, the following vulnerability has been resolved: can: vxcan: vxcan_xmit: fix use after free bug After calling netif_rx_ni(skb), dereferencing skb is unsafe. Especially, the canfd_frame cfd which aliases skb memory is accessed after the netif_rx_ni().
SSVC
Exploitation: none Automatable: no Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2025-04-17 18:17 UTC
CWE
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: a8f820a380a2a06fc4fe1a54159067958f800929 , < 6d6dcf2399cdd26f7f5426ca8dd8366b7f2ca105 (git)
Affected: a8f820a380a2a06fc4fe1a54159067958f800929 , < 9b820875a32a3443d67bfd368e93038354e98052 (git)
Affected: a8f820a380a2a06fc4fe1a54159067958f800929 , < a24476b37167816e6352ca1a2cf3769847774f70 (git)
Affected: a8f820a380a2a06fc4fe1a54159067958f800929 , < e771a874076115df8bff27d325edfd2340e4ec69 (git)
Affected: a8f820a380a2a06fc4fe1a54159067958f800929 , < 75854cad5d80976f6ea0f0431f8cedd3bcc475cb (git)
guessed Create a notification for this product.
Linux Linux Affected: 4.12
Unaffected: 0 , < 4.12 (semver)
Unaffected: 4.14.218 , ≤ 4.14.* (semver)
Unaffected: 4.19.171 , ≤ 4.19.* (semver)
Unaffected: 5.4.93 , ≤ 5.4.* (semver)
Unaffected: 5.10.11 , ≤ 5.10.* (semver)
Unaffected: 5.11 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
Show details on NVD website

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                  "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-2021-47669",
                    "options": [
                      {
                        "Exploitation": "none"
                      },
                      {
                        "Automatable": "no"
                      },
                      {
                        "Technical Impact": "total"
                      }
                    ],
                    "role": "CISA Coordinator",
                    "timestamp": "2025-04-17T18:17:52.149604Z",
                    "version": "2.0.3"
                  },
                  "type": "ssvc"
                }
              }
            ],
            "problemTypes": [
              {
                "descriptions": [
                  {
                    "cweId": "CWE-416",
                    "description": "CWE-416 Use After Free",
                    "lang": "en",
                    "type": "CWE"
                  }
                ]
              }
            ],
            "providerMetadata": {
              "dateUpdated": "2025-04-17T18:17:53.914Z",
              "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "shortName": "CISA-ADP"
            },
            "title": "CISA ADP Vulnrichment"
          }
        ],
        "cna": {
          "affected": [
            {
              "defaultStatus": "unaffected",
              "product": "Linux",
              "programFiles": [
                "drivers/net/can/vxcan.c"
              ],
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "vendor": "Linux",
              "versions": [
                {
                  "lessThan": "6d6dcf2399cdd26f7f5426ca8dd8366b7f2ca105",
                  "status": "affected",
                  "version": "a8f820a380a2a06fc4fe1a54159067958f800929",
                  "versionType": "git"
                },
                {
                  "lessThan": "9b820875a32a3443d67bfd368e93038354e98052",
                  "status": "affected",
                  "version": "a8f820a380a2a06fc4fe1a54159067958f800929",
                  "versionType": "git"
                },
                {
                  "lessThan": "a24476b37167816e6352ca1a2cf3769847774f70",
                  "status": "affected",
                  "version": "a8f820a380a2a06fc4fe1a54159067958f800929",
                  "versionType": "git"
                },
                {
                  "lessThan": "e771a874076115df8bff27d325edfd2340e4ec69",
                  "status": "affected",
                  "version": "a8f820a380a2a06fc4fe1a54159067958f800929",
                  "versionType": "git"
                },
                {
                  "lessThan": "75854cad5d80976f6ea0f0431f8cedd3bcc475cb",
                  "status": "affected",
                  "version": "a8f820a380a2a06fc4fe1a54159067958f800929",
                  "versionType": "git"
                }
              ]
            },
            {
              "defaultStatus": "affected",
              "product": "Linux",
              "programFiles": [
                "drivers/net/can/vxcan.c"
              ],
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "vendor": "Linux",
              "versions": [
                {
                  "status": "affected",
                  "version": "4.12"
                },
                {
                  "lessThan": "4.12",
                  "status": "unaffected",
                  "version": "0",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "4.14.*",
                  "status": "unaffected",
                  "version": "4.14.218",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "4.19.*",
                  "status": "unaffected",
                  "version": "4.19.171",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "5.4.*",
                  "status": "unaffected",
                  "version": "5.4.93",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "5.10.*",
                  "status": "unaffected",
                  "version": "5.10.11",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "*",
                  "status": "unaffected",
                  "version": "5.11",
                  "versionType": "original_commit_for_fix"
                }
              ]
            }
          ],
          "cpeApplicability": [
            {
              "nodes": [
                {
                  "cpeMatch": [
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "4.14.218",
                      "versionStartIncluding": "4.12",
                      "vulnerable": true
                    },
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "4.19.171",
                      "versionStartIncluding": "4.12",
                      "vulnerable": true
                    },
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "5.4.93",
                      "versionStartIncluding": "4.12",
                      "vulnerable": true
                    },
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "5.10.11",
                      "versionStartIncluding": "4.12",
                      "vulnerable": true
                    },
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "5.11",
                      "versionStartIncluding": "4.12",
                      "vulnerable": true
                    }
                  ],
                  "negate": false,
                  "operator": "OR"
                }
              ]
            }
          ],
          "descriptions": [
            {
              "lang": "en",
              "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ncan: vxcan: vxcan_xmit: fix use after free bug\n\nAfter calling netif_rx_ni(skb), dereferencing skb is unsafe.\nEspecially, the canfd_frame cfd which aliases skb memory is accessed\nafter the netif_rx_ni()."
            }
          ],
          "metrics": [
            {
              "cvssV3_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",
                "version": "3.1"
              },
              "scenarios": [
                {
                  "lang": "en",
                  "value": "AV:L - The bug is in vxcan_xmit, reached by sending a CAN frame on a virtual vxcan interface via PF_CAN/SOCK_RAW and RTNL setup\u2014local syscalls/netlink only, not remote packet processing.\nAC:L - netif_rx_ni() runs softirq immediately and can_receive() always consume_skb()s the delivered frame, so the post-rx cfd-\u003elen access is a reliable use-after-free with no race or uncontrolled condition.\nPR:L - Creating/bringing up vxcan requires CAP_NET_ADMIN, which an unprivileged user obtains via user+network namespaces (unshare -Urn); sending on an existing up interface needs no capability.\nUI:N - The attacker creates the vxcan pair, brings it up, and sends frames entirely on their own\u2014no victim interaction is required.\nS:U - Impact is confined to the local kernel (memory corruption / privilege escalation within the same security authority); this is not a VM/IOMMU/sandbox boundary escape.\nC:H - This is a use-after-free of skb data after delivery; a dangling read of freed heap enables disclosure of reclaimed object contents (including via stats that incorporate the stale byte).\nI:H - Use-after-free of the skb data buffer is exploitable via heap reuse/spray for corruption and control-flow hijacking primitives beyond the immediate stats update.\nA:H - Dereferencing freed skb data can oops/panic the kernel when the page is reclaimed or unmapped, and UAF faults are reliably triggerable on the success path."
                }
              ]
            }
          ],
          "providerMetadata": {
            "dateUpdated": "2026-08-05T08:48:49.266Z",
            "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "shortName": "Linux"
          },
          "references": [
            {
              "url": "https://git.kernel.org/stable/c/6d6dcf2399cdd26f7f5426ca8dd8366b7f2ca105"
            },
            {
              "url": "https://git.kernel.org/stable/c/9b820875a32a3443d67bfd368e93038354e98052"
            },
            {
              "url": "https://git.kernel.org/stable/c/a24476b37167816e6352ca1a2cf3769847774f70"
            },
            {
              "url": "https://git.kernel.org/stable/c/e771a874076115df8bff27d325edfd2340e4ec69"
            },
            {
              "url": "https://git.kernel.org/stable/c/75854cad5d80976f6ea0f0431f8cedd3bcc475cb"
            }
          ],
          "title": "can: vxcan: vxcan_xmit: fix use after free bug",
          "x_generator": {
            "engine": "bippy-1.2.0"
          }
        }
      },
      "cveMetadata": {
        "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "assignerShortName": "Linux",
        "cveId": "CVE-2021-47669",
        "datePublished": "2025-04-17T18:01:29.979Z",
        "dateReserved": "2025-04-16T07:16:05.752Z",
        "dateUpdated": "2026-08-05T08:48:49.266Z",
        "state": "PUBLISHED"
      },
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



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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

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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
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