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smb: client: bound dirent name against end of SMB response in cifs_filldir

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: smb: client: bound dirent name against end of SMB response in cifs_filldir cifs_filldir() copies the entry name out of an SMB1 TRANS2_FIND_FIRST / FIND_NEXT response using a length (de.namelen) supplied by the server. The kmalloc'd SMB response buffer is bounded, but nothing checks that de.name + de.namelen still lies inside that buffer before the eventual filldir64() -> verify_dirent_name() -> memchr() reads namelen bytes. A hostile SMB1 server that returns an oversized FileNameLength in a directory entry therefore causes memchr() to read past the end of the response slab buffer. Reachable from any user who can list a directory on a CIFS mount served by an attacker-controlled server (getdents64() on the mounted directory): BUG: KASAN: slab-out-of-bounds in memchr+0x71/0x80 Read of size 1 at addr ffff88800e0640cc by task poc/115 Call Trace: dump_stack_lvl+0x64/0x80 print_report+0xce/0x620 kasan_report+0xec/0x120 memchr+0x71/0x80 filldir64+0x4c/0x6a0 cifs_filldir.constprop.0+0x9bb/0x1e00 cifs_readdir+0x2101/0x3380 iterate_dir+0x19c/0x520 __x64_sys_getdents64+0x126/0x210 do_syscall_64+0x107/0x5a0 entry_SYSCALL_64_after_hwframe+0x77/0x7f Pass the end-of-response pointer down to cifs_filldir() and reject entries whose name would extend past that boundary. This bug was discovered by Artiphishell's vTriage pipeline, which generated a userspace reproducer (an emulated hostile SMB1 server plus a getdents64() client)

Announced Source revision 1
Original source ↗

CVE-2026-93787

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-93787

Linux

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Linux

Source reference: /containers/cna/affected/1/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
        "lessThan": "4cb3d79beee0fecc739ce07af915d503f29ae557",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
        "lessThan": "cf87ef1e62ed31a439064cef69d6eec38c68bd92",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
        "lessThan": "6e3b965267b7313903baba2739992b1e2e92d540",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
        "lessThan": "03003506c86f90312b0966283662c42fcab66e4b",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
        "lessThan": "f8cf09a53a0dc1da298e9dd0ba5f21710cf119d6",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "fs/smb/client/readdir.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "2.6.12"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "2.6.12",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "6.1.189",
        "versionType": "semver",
        "lessThanOrEqual": "6.1.*"
      },
      {
        "status": "unaffected",
        "version": "6.6.158",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.111",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.53",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "7.2",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "fs/smb/client/readdir.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-93787

Source reference: /cveMetadata/cveId

Publisher severity

high

Source reference: /containers/cna/metrics

Event
#8266 · Revision 1
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Publisher date
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