GHSA-7JFX-377J-9V79

Vulnerability from github – Published: 2026-07-19 18:31 – Updated: 2026-07-20 15:31
VLAI
Details

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

batman-adv: tt: fix negative last_changeset_len

batadv_piv_tt::last_changeset_len len was declared as s16, but the field is never intended to hold a negative value. When a value greater than 32767 is assigned, it wraps to a negative signed integer.

In batadv_send_my_tt_response(), last_changeset_len is temporarily widened to s32. The incorrectly negative s16 value propagates into the s32, causing batadv_tt_prepare_tvlv_local_data() to allocate a full sized buffer but populates only a small portion of it with the collected changeset. All remaining bits are kept uninitialized.

Using an u16 avoids this type confusion and ensures that no (negative) sign extension is performed in batadv_send_my_tt_response().

Severity
9.8 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2026-64089"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-19T16:17:49Z",
    "severity": "CRITICAL"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbatman-adv: tt: fix negative last_changeset_len\n\nbatadv_piv_tt::last_changeset_len len was declared as s16, but the field is\nnever intended to hold a negative value. When a value greater than 32767 is\nassigned, it wraps to a negative signed integer.\n\nIn batadv_send_my_tt_response(), last_changeset_len is temporarily widened\nto s32. The incorrectly negative s16 value propagates into the s32, causing\nbatadv_tt_prepare_tvlv_local_data() to allocate a full sized buffer but\npopulates only a small portion of it with the collected changeset. All\nremaining bits are kept uninitialized.\n\nUsing an u16 avoids this type confusion and ensures that no (negative) sign\nextension is performed in batadv_send_my_tt_response().",
  "id": "GHSA-7jfx-377j-9v79",
  "modified": "2026-07-20T15:31:59Z",
  "published": "2026-07-19T18:31:51Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64089"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/179eb62506a02d00370bd6478898cb632e10986c"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/22d59c72f4a47ffec121d0610f70d0d70c3c11c8"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/55dc41fe8821e9a849e147255ad572bc933a9d15"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6314089acf0ddf64376fdc0b1420695504c73f52"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c424e8519ac78eac5d9f4eecf06208a0d619ec14"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d29abf70c665730e249d2ec8e1402095ae26bcee"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/eb235472b52ef36981c5aad330485eaf2382c53b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/fc92cdfcb295cefa4344d71a527d61b638b7bfc4"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}



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