CVE-2021-47107

  1. OpenCVE
  2. Vulnerabilities (CVE)
  3. CVE-2021-47107
In the Linux kernel, the following vulnerability has been resolved: NFSD: Fix READDIR buffer overflow If a client sends a READDIR count argument that is too small (say, zero), then the buffer size calculation in the new init_dirlist helper functions results in an underflow, allowing the XDR stream functions to write beyond the actual buffer. This calculation has always been suspect. NFSD has never sanity- checked the READDIR count argument, but the old entry encoders managed the problem correctly. With the commits below, entry encoding changed, exposing the underflow to the pointer arithmetic in xdr_reserve_space(). Modern NFS clients attempt to retrieve as much data as possible for each READDIR request. Also, we have no unit tests that exercise the behavior of READDIR at the lower bound of @count values. Thus this case was missed during testing.

7.8 /10

CVSS v3 : HIGH

V3 Legend

Vector :

Exploitability : 1.8 / Impact : 5.9

Attack Vector LOCAL

Attack Complexity LOW

Privileges Required LOW

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact HIGH

Scope UNCHANGED

References
Link Resource
https://git.kernel.org/stable/c/53b1119a6e5028b125f431a0116ba73510d82a72 Exploit Mailing List Patch
https://git.kernel.org/stable/c/9e291a6a28d32545ed2fd959a8165144d1724df1 Exploit Mailing List Patch
https://git.kernel.org/stable/c/eabc0aab98e5218ceecd82069b0d6fdfff5ee885 Exploit Mailing List Patch
https://git.kernel.org/stable/c/53b1119a6e5028b125f431a0116ba73510d82a72 Exploit Mailing List Patch
https://git.kernel.org/stable/c/9e291a6a28d32545ed2fd959a8165144d1724df1 Exploit Mailing List Patch
https://git.kernel.org/stable/c/eabc0aab98e5218ceecd82069b0d6fdfff5ee885 Exploit Mailing List Patch
Configurations

Configuration 1 (hide)

OR cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.16:rc1:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.16:rc2:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.16:rc3:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.16:rc4:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.16:rc5:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.16:rc6:*:*:*:*:*:*
History

14 Feb 2025, 15:22

Type Values Removed Values Added
References () https://git.kernel.org/stable/c/53b1119a6e5028b125f431a0116ba73510d82a72 - () https://git.kernel.org/stable/c/53b1119a6e5028b125f431a0116ba73510d82a72 - Exploit, Mailing List, Patch
References () https://git.kernel.org/stable/c/9e291a6a28d32545ed2fd959a8165144d1724df1 - () https://git.kernel.org/stable/c/9e291a6a28d32545ed2fd959a8165144d1724df1 - Exploit, Mailing List, Patch
References () https://git.kernel.org/stable/c/eabc0aab98e5218ceecd82069b0d6fdfff5ee885 - () https://git.kernel.org/stable/c/eabc0aab98e5218ceecd82069b0d6fdfff5ee885 - Exploit, Mailing List, Patch
CPE cpe:2.3:o:linux:linux_kernel:5.16:rc3:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.16:rc6:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.16:rc5:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.16:rc4:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.16:rc2:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.16:rc1:*:*:*:*:*:*
CWE CWE-120
CVSS v2 : unknown
v3 : unknown 		v2 : unknown
v3 : 7.8
First Time Linux
Linux linux Kernel

21 Nov 2024, 06:35

Type Values Removed Values Added
References () https://git.kernel.org/stable/c/53b1119a6e5028b125f431a0116ba73510d82a72 - () https://git.kernel.org/stable/c/53b1119a6e5028b125f431a0116ba73510d82a72 -
References () https://git.kernel.org/stable/c/9e291a6a28d32545ed2fd959a8165144d1724df1 - () https://git.kernel.org/stable/c/9e291a6a28d32545ed2fd959a8165144d1724df1 -
References () https://git.kernel.org/stable/c/eabc0aab98e5218ceecd82069b0d6fdfff5ee885 - () https://git.kernel.org/stable/c/eabc0aab98e5218ceecd82069b0d6fdfff5ee885 -

21 Jun 2024, 14:15

Type Values Removed Values Added
References
  • () https://git.kernel.org/stable/c/9e291a6a28d32545ed2fd959a8165144d1724df1 -

05 Mar 2024, 13:41

Type Values Removed Values Added
Summary
  • (es) En el kernel de Linux, se resolvió la siguiente vulnerabilidad: NFSD: corrige el desbordamiento del búfer READDIR Si un cliente envía un argumento de recuento READDIR que es demasiado pequeño (digamos, cero), entonces el cálculo del tamaño del búfer en las nuevas funciones auxiliares init_dirlist da como resultado un subdesbordamiento, lo que permite que las funciones de flujo XDR escriban más allá del búfer real. Este cálculo siempre ha sido sospechoso. NFSD nunca ha verificado la cordura del argumento de conteo READDIR, pero los codificadores de entrada antiguos manejaron el problema correctamente. Con las confirmaciones a continuación, la codificación de entrada cambió, exponiendo el desbordamiento a la aritmética del puntero en xdr_reserve_space(). Los clientes NFS modernos intentan recuperar la mayor cantidad de datos posible para cada solicitud READDIR. Además, no tenemos pruebas unitarias que ejerzan el comportamiento de READDIR en el límite inferior de los valores @count. Por lo tanto, este caso se pasó por alto durante las pruebas.

04 Mar 2024, 19:15

Type Values Removed Values Added
New CVE
Information

Published : 2024-03-04 19:15

Updated : 2025-02-14 15:22

NVD link : CVE-2021-47107

Mitre link : CVE-2021-47107

CVE.ORG link : CVE-2021-47107

JSON object : View

Products Affected

linux

  • linux_kernel
CWE
CWE-120

Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')