FKIE_CVE-2026-53208

Vulnerability from fkie_nvd - Published: 2026-06-25 09:16 - Updated: 2026-07-02 20:55
Severity
5.5 (Medium) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: reject BR/EDR signaling packets over MTUsig net/bluetooth/l2cap_core.c:l2cap_sig_channel() accepts BR/EDR signaling packets up to the channel MTU and dispatches each command without enforcing the signaling MTU (MTUsig). A Bluetooth BR/EDR peer within radio range can send a fixed-channel CID 0x0001 packet that is larger than MTUsig and contains many L2CAP_ECHO_REQ commands before pairing. In a real-radio stock-kernel run, one 681-byte signaling packet containing 168 zero-length ECHO_REQ commands made the target transmit 168 ECHO_RSP frames over about 220 ms. Impact: a Bluetooth BR/EDR peer within radio range, before pairing, can force 168 ECHO_RSP frames from one 681-byte fixed-channel signaling packet containing packed ECHO_REQ commands. Define Linux's BR/EDR signaling MTU as the spec minimum of 48 bytes and reject any larger signaling packet with one L2CAP_COMMAND_REJECT_RSP carrying L2CAP_REJ_MTU_EXCEEDED before any command is dispatched. The Bluetooth Core spec wording for MTUExceeded says the reject identifier shall match the first request command in the packet, and that packets containing only responses shall be silently discarded. Linux intentionally deviates from that prescription: silently discarding desynchronizes the peer because the remote stack never learns its responses were dropped, and locating the first request command requires walking command headers past MTUsig, i.e. processing bytes from a packet we have already decided is too large to process. We therefore always emit one reject and use the identifier from the first command header, a single fixed-offset byte read. The unrestricted BR/EDR signaling parser and ECHO_REQ response path both trace to the initial git import; no later introducing commit is available for a Fixes tag.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/214a2042b16b3c8d798a8b9ef9f36094f13a9859Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/a8335f3db15bd1e0e82e0db5d488fabc7d10d1abPatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/b20e8a98dd29b121f58fcdf51e8576119aba536aPatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/dd214733544427587a95f66dbf3adff072568990Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/dedc92b96dc1d8919a3bdf2495ede68922ef7ebcPatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/e05c4ac575b457978a7ef441053394169084869cPatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/e2b8acf9405bd9b1baf1c54dc897b0905db689bfPatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/fa5823126239b3e453fac1a2fe50726c7f4a55e1Patch
Impacted products
Vendor Product Version
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel 2.6.12
linux linux_kernel 2.6.12
linux linux_kernel 2.6.12
linux linux_kernel 2.6.12
linux linux_kernel 2.6.12
linux linux_kernel 7.1
linux linux_kernel 7.1
linux linux_kernel 7.1
linux linux_kernel 7.1
linux linux_kernel 7.1
linux linux_kernel 7.1
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "include/net/bluetooth/l2cap.h",
            "net/bluetooth/l2cap_core.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "e05c4ac575b457978a7ef441053394169084869c",
              "status": "affected",
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "versionType": "git"
            },
            {
              "lessThan": "fa5823126239b3e453fac1a2fe50726c7f4a55e1",
              "status": "affected",
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "versionType": "git"
            },
            {
              "lessThan": "b20e8a98dd29b121f58fcdf51e8576119aba536a",
              "status": "affected",
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "versionType": "git"
            },
            {
              "lessThan": "214a2042b16b3c8d798a8b9ef9f36094f13a9859",
              "status": "affected",
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "versionType": "git"
            },
            {
              "lessThan": "a8335f3db15bd1e0e82e0db5d488fabc7d10d1ab",
              "status": "affected",
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "versionType": "git"
            },
            {
              "lessThan": "dedc92b96dc1d8919a3bdf2495ede68922ef7ebc",
              "status": "affected",
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "versionType": "git"
            },
            {
              "lessThan": "e2b8acf9405bd9b1baf1c54dc897b0905db689bf",
              "status": "affected",
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "versionType": "git"
            },
            {
              "lessThan": "dd214733544427587a95f66dbf3adff072568990",
              "status": "affected",
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "include/net/bluetooth/l2cap.h",
            "net/bluetooth/l2cap_core.c"
          ],
          "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": "5.10.*",
              "status": "unaffected",
              "version": "5.10.259",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.210",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.176",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.143",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.94",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.36",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.0.*",
              "status": "unaffected",
              "version": "7.0.13",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "1D09A811-8082-4A08-AF10-F1F8501C5596",
              "versionEndExcluding": "5.10.259",
              "versionStartIncluding": "2.6.12.1",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "5E938CDF-D1C4-43D0-98DC-9E11B6B55801",
              "versionEndExcluding": "5.15.210",
              "versionStartIncluding": "5.11",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "C4446623-5F2B-4DD8-8666-9FAAC285A757",
              "versionEndExcluding": "6.1.176",
              "versionStartIncluding": "5.16",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "9062F1CD-CAD6-4EA2-A73F-C06D4A887B8C",
              "versionEndExcluding": "6.6.143",
              "versionStartIncluding": "6.2",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "85421C0C-ABDE-4357-971C-67F9087DE1B9",
              "versionEndExcluding": "6.12.94",
              "versionStartIncluding": "6.7",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "389025D2-958D-41BD-BD96-70ED1033A9F3",
              "versionEndExcluding": "6.18.36",
              "versionStartIncluding": "6.13",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "6A64BF9F-3BCA-42FD-98CB-8F03474D2B1E",
              "versionEndExcluding": "7.0.13",
              "versionStartIncluding": "6.19",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:2.6.12:-:*:*:*:*:*:*",
              "matchCriteriaId": "6F62EECE-8FB1-4D57-85D8-CB9E23CF313C",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:2.6.12:rc2:*:*:*:*:*:*",
              "matchCriteriaId": "4F76C298-81DC-43E4-8FC9-DC005A2116EF",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:2.6.12:rc3:*:*:*:*:*:*",
              "matchCriteriaId": "0AB349B2-3F78-4197-882B-90ADB3BF645A",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:2.6.12:rc4:*:*:*:*:*:*",
              "matchCriteriaId": "6AC88830-A9BC-4607-B572-A4B502FC9FD0",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:2.6.12:rc5:*:*:*:*:*:*",
              "matchCriteriaId": "476CB3A5-D022-4F13-AAEF-CB6A5785516A",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:*",
              "matchCriteriaId": "B1EF7059-E670-45F4-B422-54C40FA86390",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:7.1:rc2:*:*:*:*:*:*",
              "matchCriteriaId": "0D38F0BF-A728-4133-A358-D44A2F7EE6D6",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:7.1:rc3:*:*:*:*:*:*",
              "matchCriteriaId": "EC732D08-5F7B-46D9-B154-E60C7F4F0A97",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:7.1:rc4:*:*:*:*:*:*",
              "matchCriteriaId": "E5910A9D-F60A-409A-B486-FE66BFEBA9B9",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:7.1:rc5:*:*:*:*:*:*",
              "matchCriteriaId": "81DFF19E-9CF8-49C6-8C36-1E4038622933",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:7.1:rc6:*:*:*:*:*:*",
              "matchCriteriaId": "B0E8FC71-3952-444C-83E9-718DBBBEC615",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: L2CAP: reject BR/EDR signaling packets over MTUsig\n\nnet/bluetooth/l2cap_core.c:l2cap_sig_channel() accepts BR/EDR\nsignaling packets up to the channel MTU and dispatches each command\nwithout enforcing the signaling MTU (MTUsig). A Bluetooth BR/EDR peer\nwithin radio range can send a fixed-channel CID 0x0001 packet that is\nlarger than MTUsig and contains many L2CAP_ECHO_REQ commands before\npairing. In a real-radio stock-kernel run, one 681-byte signaling\npacket containing 168 zero-length ECHO_REQ commands made the target\ntransmit 168 ECHO_RSP frames over about 220 ms.\n\nImpact: a Bluetooth BR/EDR peer within radio range, before pairing, can\nforce 168 ECHO_RSP frames from one 681-byte fixed-channel signaling\npacket containing packed ECHO_REQ commands.\n\nDefine Linux\u0027s BR/EDR signaling MTU as the spec minimum of 48 bytes and\nreject any larger signaling packet with one L2CAP_COMMAND_REJECT_RSP\ncarrying L2CAP_REJ_MTU_EXCEEDED before any command is dispatched.\n\nThe Bluetooth Core spec wording for MTUExceeded says the reject\nidentifier shall match the first request command in the packet, and\nthat packets containing only responses shall be silently discarded.\nLinux intentionally deviates from that prescription: silently\ndiscarding desynchronizes the peer because the remote stack never\nlearns its responses were dropped, and locating the first request\ncommand requires walking command headers past MTUsig, i.e. processing\nbytes from a packet we have already decided is too large to process.\nWe therefore always emit one reject and use the identifier from the\nfirst command header, a single fixed-offset byte read.\n\nThe unrestricted BR/EDR signaling parser and ECHO_REQ response path both\ntrace to the initial git import; no later introducing commit is\navailable for a Fixes tag."
    }
  ],
  "id": "CVE-2026-53208",
  "lastModified": "2026-07-02T20:55:04.500",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 5.5,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 3.6,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ]
  },
  "published": "2026-06-25T09:16:38.350",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/214a2042b16b3c8d798a8b9ef9f36094f13a9859"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/a8335f3db15bd1e0e82e0db5d488fabc7d10d1ab"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/b20e8a98dd29b121f58fcdf51e8576119aba536a"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/dd214733544427587a95f66dbf3adff072568990"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/dedc92b96dc1d8919a3bdf2495ede68922ef7ebc"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/e05c4ac575b457978a7ef441053394169084869c"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/e2b8acf9405bd9b1baf1c54dc897b0905db689bf"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/fa5823126239b3e453fac1a2fe50726c7f4a55e1"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "NVD-CWE-noinfo"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}


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.