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cifs: prevent NULL pointer dereference in UTF16 conversion

Type: advisorySources: OSV

In the Linux kernel, the following vulnerability has been resolved: cifs: prevent NULL pointer dereference in UTF16 conversion There can be a NULL pointer dereference bug here. NULL is passed to __cifs_sfu_make_node without checks, which passes it unchecked to cifs_strndup_to_utf16, which in turn passes it to cifs_local_to_utf16_bytes where '*from' is dereferenced, causing a crash. This patch adds a check for NULL 'src' in cifs_strndup_to_utf16 and returns NULL early to prevent dereferencing NULL pointer. Found by Linux Verification Center (linuxtesting.org) with SVACE

Products
Kernel
Affected versions
Not specified
Fixed versions
6.12.46, 6.16.6
CVEs
CVE-2025-39838
Confirmed fixed CVEs
Not specified
Updated in this feed
5 Nov 2026, 01:44 UTC · Revision 1

Source evidence

cifs: prevent NULL pointer dereference in UTF16 conversion

core-osv · Original source

Published 19 Sept 2025, 15:26 UTC

In the Linux kernel, the following vulnerability has been resolved: cifs: prevent NULL pointer dereference in UTF16 conversion There can be a NULL pointer dereference bug here. NULL is passed to __cifs_sfu_make_node without checks, which passes it unchecked to cifs_strndup_to_utf16, which in turn passes it to cifs_local_to_utf16_bytes where '*from' is dereferenced, causing a crash. This patch adds a check for NULL 'src' in cifs_strndup_to_utf16 and returns NULL early to prevent dereferencing NULL pointer. Found by Linux Verification Center (linuxtesting.org) with SVACE

osv:CVE-2025-39838

Kernel

Fixed versions: 6.12.46, 6.16.6

Complete source record
{
  "id": "9ef96d9274e325caa09b3ab52742cef004d60014f6c80db5f4600ff31ef9bf4d",
  "url": "https://osv.dev/vulnerability/CVE-2025-39838",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "cifs: prevent NULL pointer dereference in UTF16 conversion",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: cifs: prevent NULL pointer dereference in UTF16 conversion There can be a NULL pointer dereference bug here. NULL is passed to __cifs_sfu_make_node without checks, which passes it unchecked to cifs_strndup_to_utf16, which in turn passes it to cifs_local_to_utf16_bytes where '*from' is dereferenced, causing a crash. This patch adds a check for NULL 'src' in cifs_strndup_to_utf16 and returns NULL early to prevent dereferencing NULL pointer. Found by Linux Verification Center (linuxtesting.org) with SVACE",
    "evidence": "osv:CVE-2025-39838",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.12.46",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.16.6",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2025-39838",
      "aliases": [
        "CVE-2025-39838"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "41d3f256c6a5e41eb32b87168399c0facd512dc0"
                },
                {
                  "fixed": "1f797f062b5cf13a1c2bcc23285361baaa7c9260"
                },
                {
                  "fixed": "3c26a8d30ed6b53a52a023ec537dc50a6d34a67a"
                },
                {
                  "fixed": "70bccd9855dae56942f2b18a08ba137bb54093a0"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-39838.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.12.0"
                },
                {
                  "fixed": "6.12.46"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.13.0"
                },
                {
                  "fixed": "6.16.6"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-39838.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:41.412408342Z",
      "provider": "osv",
      "references": [
        "https://cert-portal.siemens.com/productcert/html/ssa-032379.html",
        "https://git.kernel.org/stable/c/1f797f062b5cf13a1c2bcc23285361baaa7c9260",
        "https://git.kernel.org/stable/c/3c26a8d30ed6b53a52a023ec537dc50a6d34a67a",
        "https://git.kernel.org/stable/c/70bccd9855dae56942f2b18a08ba137bb54093a0",
        "https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/39xxx/CVE-2025-39838.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2025-39838",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/39xxx/CVE-2025-39838.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2025-39838",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 509179,
  "published_at": "2025-09-19T15:26:13.506+00:00"
}