---
cve: "CVE-2026-93787"
severity: "HIGH"
cvss: 8.1
epss: "0.3%"
vendor: "Linux"
kev: false
exploited: false
published: "2026-09-24 16:02:20"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-10-09T12:23:47+02:00"
---

# CVE-2026-93787

> 8.1 HIGH

## Beschreibung

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) that reliably triggers the KASAN report on an
unpatched kernel. The fix below was drafted with the Claude coding
assistant; a userspace reproducer is available on request.

## CNA-Record (Kanon, cvelistV5)

- CNA: **Linux**
- State: PUBLISHED
- Stand: 2026-10-03 10:57:22
- CNA-CVSS: **8.1** (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H`)

## CVSS-Vektor

```
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Erforderlich | good |
| S Scope | Unverändert | good |
| C Vertraulichkeit | Hoch | bad |
| I Integrität | Keine | good |
| A Verfügbarkeit | Hoch | bad |

## Patch verfügbar (OSV)

- Kernel ≥ 6.1.189
- Kernel ≥ 6.6.158
- Kernel ≥ 6.12.111
- Kernel ≥ 6.18.53

## BSI-Hinweise (deutsch)

- [Linux Kernel: Mehrere Schwachstellen](https://wid.cert-bund.de/portal/wid/sicherheitshinweis/WID-SEC-W-2026-3579) — _BSI-Einstufung: mittel_
  Ein lokaler Angreifer kann mehrere Schwachstellen im Linux Kernel ausnutzen, um einen Denial of Service Zustand herbeizuführen oder nicht näher spezifizierten Angriff durchzuführen.

## Referenzen

- <https://git.kernel.org/stable/c/4cb3d79beee0fecc739ce07af915d503f29ae557>
- <https://git.kernel.org/stable/c/cf87ef1e62ed31a439064cef69d6eec38c68bd92>
- <https://git.kernel.org/stable/c/6e3b965267b7313903baba2739992b1e2e92d540>
- <https://git.kernel.org/stable/c/03003506c86f90312b0966283662c42fcab66e4b>
- <https://git.kernel.org/stable/c/f8cf09a53a0dc1da298e9dd0ba5f21710cf119d6>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/sicherheitsluecken/cve-2026-93787/) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI WID (CSAF)_