GHSA-59WX-RWXR-9VQ7

Vulnerability from github – Published: 2026-04-22 15:31 – Updated: 2026-04-28 15:30
VLAI?
Details

In the Linux kernel, the following vulnerability has been resolved:

Bluetooth: L2CAP: Fix ERTM re-init and zero pdu_len infinite loop

l2cap_config_req() processes CONFIG_REQ for channels in BT_CONNECTED state to support L2CAP reconfiguration (e.g. MTU changes). However, since both CONF_INPUT_DONE and CONF_OUTPUT_DONE are already set from the initial configuration, the reconfiguration path falls through to l2cap_ertm_init(), which re-initializes tx_q, srej_q, srej_list, and retrans_list without freeing the previous allocations and sets chan->sdu to NULL without freeing the existing skb. This leaks all previously allocated ERTM resources.

Additionally, l2cap_parse_conf_req() does not validate the minimum value of remote_mps derived from the RFC max_pdu_size option. A zero value propagates to l2cap_segment_sdu() where pdu_len becomes zero, causing the while loop to never terminate since len is never decremented, exhausting all available memory.

Fix the double-init by skipping l2cap_ertm_init() and l2cap_chan_ready() when the channel is already in BT_CONNECTED state, while still allowing the reconfiguration parameters to be updated through l2cap_parse_conf_req(). Also add a pdu_len zero check in l2cap_segment_sdu() as a safeguard.

Severity ?
5.5 (Medium)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2026-31498"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-835"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-04-22T14:16:48Z",
    "severity": "MODERATE"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: L2CAP: Fix ERTM re-init and zero pdu_len infinite loop\n\nl2cap_config_req() processes CONFIG_REQ for channels in BT_CONNECTED\nstate to support L2CAP reconfiguration (e.g. MTU changes). However,\nsince both CONF_INPUT_DONE and CONF_OUTPUT_DONE are already set from\nthe initial configuration, the reconfiguration path falls through to\nl2cap_ertm_init(), which re-initializes tx_q, srej_q, srej_list, and\nretrans_list without freeing the previous allocations and sets\nchan-\u003esdu to NULL without freeing the existing skb. This leaks all\npreviously allocated ERTM resources.\n\nAdditionally, l2cap_parse_conf_req() does not validate the minimum\nvalue of remote_mps derived from the RFC max_pdu_size option. A zero\nvalue propagates to l2cap_segment_sdu() where pdu_len becomes zero,\ncausing the while loop to never terminate since len is never\ndecremented, exhausting all available memory.\n\nFix the double-init by skipping l2cap_ertm_init() and\nl2cap_chan_ready() when the channel is already in BT_CONNECTED state,\nwhile still allowing the reconfiguration parameters to be updated\nthrough l2cap_parse_conf_req(). Also add a pdu_len zero check in\nl2cap_segment_sdu() as a safeguard.",
  "id": "GHSA-59wx-rwxr-9vq7",
  "modified": "2026-04-28T15:30:47Z",
  "published": "2026-04-22T15:31:43Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-31498"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/042e2cd4bb11e5313b19b87593616524949e4c52"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/25f420a0d4cfd61d3d23ec4b9c56d9f443d91377"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/52667c859fe33f70c2e711cb81bbd505d5eb8e75"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/900e4db5385ec2cacd372345a80ab9c8e105b3a3"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9760b83cfd24b38caee663f429011a0dd6064fa9"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9a21a631ee034b1573dce14b572a24943dbfd7ae"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/de37e2655b7abc3f59254c6b72256840f39fc6d5"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e7aab23b7df89a3d754a5f0a7d2237548b328bd0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}


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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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