GHSA-QQ5R-FPG9-2MJ7

Vulnerability from github – Published: 2025-09-05 18:31 – Updated: 2026-01-09 00:30
VLAI?
Details

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

fbdev: Fix vmalloc out-of-bounds write in fast_imageblit

This issue triggers when a userspace program does an ioctl FBIOPUT_CON2FBMAP by passing console number and frame buffer number. Ideally this maps console to frame buffer and updates the screen if console is visible.

As part of mapping it has to do resize of console according to frame buffer info. if this resize fails and returns from vc_do_resize() and continues further. At this point console and new frame buffer are mapped and sets display vars. Despite failure still it continue to proceed updating the screen at later stages where vc_data is related to previous frame buffer and frame buffer info and display vars are mapped to new frame buffer and eventully leading to out-of-bounds write in fast_imageblit(). This bheviour is excepted only when fg_console is equal to requested console which is a visible console and updates screen with invalid struct references in fbcon_putcs().

Severity ?
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2025-38685"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-787"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-09-04T16:15:36Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nfbdev: Fix vmalloc out-of-bounds write in fast_imageblit\n\nThis issue triggers when a userspace program does an ioctl\nFBIOPUT_CON2FBMAP by passing console number and frame buffer number.\nIdeally this maps console to frame buffer and updates the screen if\nconsole is visible.\n\nAs part of mapping it has to do resize of console according to frame\nbuffer info. if this resize fails and returns from vc_do_resize() and\ncontinues further. At this point console and new frame buffer are mapped\nand sets display vars. Despite failure still it continue to proceed\nupdating the screen at later stages where vc_data is related to previous\nframe buffer and frame buffer info and display vars are mapped to new\nframe buffer and eventully leading to out-of-bounds write in\nfast_imageblit(). This bheviour is excepted only when fg_console is\nequal to requested console which is a visible console and updates screen\nwith invalid struct references in fbcon_putcs().",
  "id": "GHSA-qq5r-fpg9-2mj7",
  "modified": "2026-01-09T00:30:27Z",
  "published": "2025-09-05T18:31:15Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-38685"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/078e62bffca4b7e72e8f3550eb063ab981c36c7a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/27b118aebdd84161c8ff5ce49d9d536f2af10754"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4c4d7ddaf1d43780b106bedc692679f965dc5a3a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/56701bf9eeb63219e378cb7fcbd066ea4eaeeb50"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/af0db3c1f898144846d4c172531a199bb3ca375d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/cfec17721265e72e50cc69c6004fe3475cd38df2"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ed9b8e5016230868c8d813d9179523f729fec8c6"
    },
    {
      "type": "WEB",
      "url": "https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}


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