GHSA-WQWG-V9CC-CPQ7

Vulnerability from github – Published: 2026-07-25 12:31 – Updated: 2026-07-27 06:30
VLAI
Details

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

Bluetooth: L2CAP: validate option length before reading conf opt value

l2cap_get_conf_opt() derives the option length from the attacker-controlled opt->len field and immediately dereferences opt->val (as u8, get_unaligned_le16() or get_unaligned_le32(), or a raw pointer for the default case) before any caller has confirmed that opt->len bytes are present in the buffer. The callers (l2cap_parse_conf_req(), l2cap_parse_conf_rsp() and l2cap_conf_rfc_get()) only detect a malformed option afterwards, once the running length has gone negative, by which point the out-of-bounds read has already executed.

An existing post-hoc length check keeps the garbage value from being consumed, so this is not a data leak in the current control flow. It is still a validate-after-use ordering bug: up to 4 bytes are read past the end of the buffer before it is known to contain them, and it is fragile to future changes in the callers.

Fix it at the source. Pass the end of the buffer into l2cap_get_conf_opt() and refuse to touch opt->val unless the full option (header + value) fits. Each caller computes an end pointer once before the loop and checks the return value directly instead of inferring the error from a negative length.

Severity
7.1 (High)
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2026-64403"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-125",
      "CWE-476"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-25T10:17:23Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: L2CAP: validate option length before reading conf opt value\n\nl2cap_get_conf_opt() derives the option length from the\nattacker-controlled opt-\u003elen field and immediately dereferences\nopt-\u003eval (as u8, get_unaligned_le16() or get_unaligned_le32(), or a\nraw pointer for the default case) before any caller has confirmed\nthat opt-\u003elen bytes are present in the buffer. The callers\n(l2cap_parse_conf_req(), l2cap_parse_conf_rsp() and\nl2cap_conf_rfc_get()) only detect a malformed option afterwards, once\nthe running length has gone negative, by which point the\nout-of-bounds read has already executed.\n\nAn existing post-hoc length check keeps the garbage value from being\nconsumed, so this is not a data leak in the current control flow. It\nis still a validate-after-use ordering bug: up to 4 bytes are read\npast the end of the buffer before it is known to contain them, and it\nis fragile to future changes in the callers.\n\nFix it at the source. Pass the end of the buffer into\nl2cap_get_conf_opt() and refuse to touch opt-\u003eval unless the full\noption (header + value) fits. Each caller computes an end pointer\nonce before the loop and checks the return value directly instead of\ninferring the error from a negative length.",
  "id": "GHSA-wqwg-v9cc-cpq7",
  "modified": "2026-07-27T06:30:36Z",
  "published": "2026-07-25T12:31:34Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64403"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/687617555cedfb74c9e3cb85d759b908dcb17856"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6b47bdaacfd0045687880177e0987055d8f4765a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/73abbaf91aa33da87c008fb62c148ade561bb606"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7d871e969b941ce25653f7716203a0ea4d07ad4b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/98d93c226bdfaa79bbdd86981921d7f106374225"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/996d3da39899aceb8f4910911a3f19a45a7d9d1b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/cca81b4bc672604a84f6d224a55cc77ec7dee619"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f70d4aa88068096f35d73e3a05eff33c0a16b9cd"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}



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