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FKIE_CVE-2026-72333

Vulnerability from fkie_nvd - Published: 2026-08-15 06:22 - Updated: 2026-08-17 06:18
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: fix tx ident leak for commands without a response Commit 6c3ea155e5ee ("Bluetooth: L2CAP: Fix not tracking outstanding TX ident") changed ident allocation to use an IDA, releasing idents in l2cap_put_ident() when the matching response command is received. But identifiers allocated for commands that have no response defined are never released. In particular L2CAP_LE_CREDITS is sent repeatedly for the lifetime of an LE CoC channel, so a peer streaming data to the host exhausts the 1-255 ident range after 254 credit packets. From then on l2cap_get_ident() fails: kernel: Bluetooth: Unable to allocate ident: -28 and every subsequent L2CAP_LE_CREDITS packet is sent with ident 0, which is invalid (Core Spec, Vol 3, Part A, Section 4: "Signaling identifier 0x00 is an invalid identifier and shall never be used in any command"). Remote stacks that validate the ident drop these commands, never receive new credits, and the channel stalls permanently. With default socket buffers this happens after roughly 0.5 MB of received data (the exact amount depends on the socket receive buffer): < ACL Data TX: Handle 2048 flags 0x00 dlen 12 LE L2CAP: LE Flow Control Credit (0x16) ident 0 len 4 Source CID: 64 Credits: 1 Release the ident immediately after sending L2CAP_LE_CREDITS since no response will ever release it. Use a local variable instead of chan->ident so that an ident that an EXT_FLOWCTL channel may be waiting on (e.g. a pending reconfigure) is not overwritten by a credit packet. Also add the missing L2CAP_LE_CONN_RSP case to l2cap_put_ident() so idents allocated for outgoing L2CAP_LE_CONN_REQ commands are released when the response arrives.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/0c602cb8f148a36bfb39c25ade400bdadc023c4f
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/6e1930ece855a4c256f1c7e6632d634cfb9888b5
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/b8a32a5fc915b024c60f18d51b6cffd2bd64d4a6
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/bd1e01170341291292fd4c46b5f6949da282ca6c
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/d0a2b0c81f112540a337cde1c20251bf05ddf1da
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/bluetooth/l2cap_core.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "b8a32a5fc915b024c60f18d51b6cffd2bd64d4a6",
              "status": "affected",
              "version": "e86554c37d3d2b4b24608e0313f882cae28b8adb",
              "versionType": "git"
            },
            {
              "lessThan": "bd1e01170341291292fd4c46b5f6949da282ca6c",
              "status": "affected",
              "version": "9b24ad4787cad46a3917620799f8455c6533b8df",
              "versionType": "git"
            },
            {
              "lessThan": "0c602cb8f148a36bfb39c25ade400bdadc023c4f",
              "status": "affected",
              "version": "ea6cf86167b3972caa68972d2a1ad43ecbbb8331",
              "versionType": "git"
            },
            {
              "lessThan": "d0a2b0c81f112540a337cde1c20251bf05ddf1da",
              "status": "affected",
              "version": "6c3ea155e5ee3e56606233acde8309afda66d483",
              "versionType": "git"
            },
            {
              "lessThan": "6e1930ece855a4c256f1c7e6632d634cfb9888b5",
              "status": "affected",
              "version": "6c3ea155e5ee3e56606233acde8309afda66d483",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "ed97bb2cf96684ee646be6f37e4c4835f9d30caa",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "84bc3197f7d87c5b89c156e853d0561a9154eceb",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "8c1cdbc1bacc0cf9c27c3ebda11a81c3dcd01630",
              "versionType": "git"
            },
            {
              "lessThan": "6.18.40",
              "status": "affected",
              "version": "6.18.21",
              "versionType": "semver"
            },
            {
              "lessThan": "5.11",
              "status": "affected",
              "version": "5.10.261",
              "versionType": "semver"
            },
            {
              "lessThan": "5.16",
              "status": "affected",
              "version": "5.15.212",
              "versionType": "semver"
            },
            {
              "lessThan": "6.20",
              "status": "affected",
              "version": "6.19.11",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/bluetooth/l2cap_core.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "7.0"
            },
            {
              "lessThan": "7.0",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.40",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.5",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: L2CAP: fix tx ident leak for commands without a response\n\nCommit 6c3ea155e5ee (\"Bluetooth: L2CAP: Fix not tracking outstanding\nTX ident\") changed ident allocation to use an IDA, releasing idents in\nl2cap_put_ident() when the matching response command is received.\n\nBut identifiers allocated for commands that have no response defined\nare never released. In particular L2CAP_LE_CREDITS is sent repeatedly for\nthe lifetime of an LE CoC channel, so a peer streaming data to the\nhost exhausts the 1-255 ident range after 254 credit packets. From\nthen on l2cap_get_ident() fails:\n\n    kernel: Bluetooth: Unable to allocate ident: -28\n\nand every subsequent L2CAP_LE_CREDITS packet is sent with ident 0,\nwhich is invalid (Core Spec, Vol 3, Part A, Section 4: \"Signaling\nidentifier 0x00 is an invalid identifier and shall never be used in\nany command\"). Remote stacks that validate the ident drop these\ncommands, never receive new credits, and the channel stalls\npermanently. With default socket buffers this happens after roughly 0.5 MB\nof received data (the exact amount depends on the socket receive buffer):\n\n  \u003c ACL Data TX: Handle 2048 flags 0x00 dlen 12\n        LE L2CAP: LE Flow Control Credit (0x16) ident 0 len 4\n          Source CID: 64\n          Credits: 1\n\nRelease the ident immediately after sending L2CAP_LE_CREDITS since no\nresponse will ever release it. Use a local variable instead of\nchan-\u003eident so that an ident that an EXT_FLOWCTL channel may be waiting on\n(e.g. a pending reconfigure) is not overwritten by a credit packet.\n\nAlso add the missing L2CAP_LE_CONN_RSP case to l2cap_put_ident() so\nidents allocated for outgoing L2CAP_LE_CONN_REQ commands are released\nwhen the response arrives."
    }
  ],
  "id": "CVE-2026-72333",
  "lastModified": "2026-08-17T06:18:36.910",
  "metrics": {},
  "published": "2026-08-15T06:22:06.433",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/0c602cb8f148a36bfb39c25ade400bdadc023c4f"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/6e1930ece855a4c256f1c7e6632d634cfb9888b5"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/b8a32a5fc915b024c60f18d51b6cffd2bd64d4a6"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/bd1e01170341291292fd4c46b5f6949da282ca6c"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/d0a2b0c81f112540a337cde1c20251bf05ddf1da"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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