CVE-2026-31392

  1. OpenCVE
  2. Vulnerabilities (CVE)
  3. CVE-2026-31392
In the Linux kernel, the following vulnerability has been resolved: smb: client: fix krb5 mount with username option Customer reported that some of their krb5 mounts were failing against a single server as the client was trying to mount the shares with wrong credentials. It turned out the client was reusing SMB session from first mount to try mounting the other shares, even though a different username= option had been specified to the other mounts. By using username mount option along with sec=krb5 to search for principals from keytab is supported by cifs.upcall(8) since cifs-utils-4.8. So fix this by matching username mount option in match_session() even with Kerberos. For example, the second mount below should fail with -ENOKEY as there is no 'foobar' principal in keytab (/etc/krb5.keytab). The client ends up reusing SMB session from first mount to perform the second one, which is wrong. ``` $ ktutil ktutil: add_entry -password -p testuser -k 1 -e aes256-cts Password for testuser@ZELDA.TEST: ktutil: write_kt /etc/krb5.keytab ktutil: quit $ klist -ke Keytab name: FILE:/etc/krb5.keytab KVNO Principal ---- ---------------------------------------------------------------- 1 testuser@ZELDA.TEST (aes256-cts-hmac-sha1-96) $ mount.cifs //w22-root2/scratch /mnt/1 -o sec=krb5,username=testuser $ mount.cifs //w22-root2/scratch /mnt/2 -o sec=krb5,username=foobar $ mount -t cifs | grep -Po 'username=\K\w+' testuser testuser ```

8.1 /10

CVSS v3 : HIGH

V3 Legend

Vector :

Exploitability : 1.5 / Impact : 6.0

Attack Vector LOCAL

Attack Complexity LOW

Privileges Required HIGH

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact LOW

Scope CHANGED

References
Link Resource
https://git.kernel.org/stable/c/12b4c5d98cd7ca46d5035a57bcd995df614c14e1 Patch
https://git.kernel.org/stable/c/6e9ff1eb7feedcf46ff2d0503759960ab58e7775 Patch
https://git.kernel.org/stable/c/9229709ec8bf85ae7ca53aeee9aa14814cdc1bd2 Patch
https://git.kernel.org/stable/c/9ee803bfdba0cf739038dbdabdd4c02582c8f2b2 Patch
https://git.kernel.org/stable/c/d33cbf0bf8979d779900da9be2505d68d9d8da25 Patch
https://git.kernel.org/stable/c/fd4547830720647d4af02ee50f883c4b1cca06e4 Patch
Configurations

Configuration 1 (hide)

OR cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:*
History

21 Jul 2026, 19:10

Type Values Removed Values Added
Summary
  • (es) En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta: smb: cliente: corregir montaje krb5 con opción de nombre de usuario El cliente informó que algunos de sus montajes krb5 estaban fallando contra un único servidor ya que el cliente estaba intentando montar los recursos compartidos con credenciales incorrectas. Resultó que el cliente estaba reutilizando la sesión SMB del primer montaje para intentar montar los otros recursos compartidos, a pesar de que una opción diferente de username= había sido especificada para los otros montajes. El uso de la opción de montaje de nombre de usuario junto con sec=krb5 para buscar principales de keytab es compatible con cifs.upcall(8) desde cifs-utils-4.8. Por lo tanto, corrija esto al hacer coincidir la opción de montaje de nombre de usuario en match_session() incluso con Kerberos. Por ejemplo, el segundo montaje a continuación debería fallar con -ENOKEY ya que no hay ningún principal foobar en keytab (/etc/krb5.keytab). El cliente termina reutilizando la sesión SMB del primer montaje para realizar el segundo, lo cual es incorrecto. ''' $ ktutil ktutil: add_entry -password -p testuser -k 1 -e aes256-cts Password for testuser@ZELDA.TEST: ktutil: write_kt /etc/krb5.keytab ktutil: quit $ klist -ke Keytab name: FILE:/etc/krb5.keytab KVNO Principal ---- ---------------------------------------------------------------- 1 testuser@ZELDA.TEST (aes256-cts-hmac-sha1-96) $ mount.cifs //w22-root2/scratch /mnt/1 -o sec=krb5,username=testuser $ mount.cifs //w22-root2/scratch /mnt/2 -o sec=krb5,username=foobar $ mount -t cifs | grep -Po username=\K\w+ testuser testuser '''

26 May 2026, 12:57

Type Values Removed Values Added
CWE NVD-CWE-noinfo
First Time Linux
Linux linux Kernel
CPE cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:*
References () https://git.kernel.org/stable/c/12b4c5d98cd7ca46d5035a57bcd995df614c14e1 - () https://git.kernel.org/stable/c/12b4c5d98cd7ca46d5035a57bcd995df614c14e1 - Patch
References () https://git.kernel.org/stable/c/6e9ff1eb7feedcf46ff2d0503759960ab58e7775 - () https://git.kernel.org/stable/c/6e9ff1eb7feedcf46ff2d0503759960ab58e7775 - Patch
References () https://git.kernel.org/stable/c/9229709ec8bf85ae7ca53aeee9aa14814cdc1bd2 - () https://git.kernel.org/stable/c/9229709ec8bf85ae7ca53aeee9aa14814cdc1bd2 - Patch
References () https://git.kernel.org/stable/c/9ee803bfdba0cf739038dbdabdd4c02582c8f2b2 - () https://git.kernel.org/stable/c/9ee803bfdba0cf739038dbdabdd4c02582c8f2b2 - Patch
References () https://git.kernel.org/stable/c/d33cbf0bf8979d779900da9be2505d68d9d8da25 - () https://git.kernel.org/stable/c/d33cbf0bf8979d779900da9be2505d68d9d8da25 - Patch
References () https://git.kernel.org/stable/c/fd4547830720647d4af02ee50f883c4b1cca06e4 - () https://git.kernel.org/stable/c/fd4547830720647d4af02ee50f883c4b1cca06e4 - Patch

27 Apr 2026, 14:16

Type Values Removed Values Added
CVSS v2 : unknown
v3 : unknown 		v2 : unknown
v3 : 8.1

03 Apr 2026, 16:16

Type Values Removed Values Added
New CVE
Information

Published : 2026-04-03 16:16

Updated : 2026-07-21 19:10

NVD link : CVE-2026-31392

Mitre link : CVE-2026-31392

CVE.ORG link : CVE-2026-31392

JSON object : View

Products Affected

linux

  • linux_kernel
CWE
NVD-CWE-noinfo