CVE-2010-0787 in Samba
Summary
by MITRE
client/mount.cifs.c in mount.cifs in smbfs in Samba 3.0.22, 3.0.28a, 3.2.3, 3.3.2, 3.4.0, and 3.4.5 allows local users to mount a CIFS share on an arbitrary mountpoint, and gain privileges, via a symlink attack on the mountpoint directory file.
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Analysis
by VulDB Data Team • 05/01/2026
The vulnerability identified as CVE-2010-0787 represents a critical privilege escalation flaw within the Samba file sharing implementation that affects multiple versions of the smbfs subsystem. This security issue resides in the client-side mount.cifs utility which is responsible for mounting CIFS shares from remote servers. The vulnerability stems from insufficient validation of mountpoint directories during the mounting process, creating an opportunity for local attackers to exploit a symbolic link attack pattern. The flaw specifically impacts Samba versions 3.0.22, 3.0.28a, 3.2.3, 3.3.2, 3.4.0, and 3.4.5, making it a widespread concern across a significant portion of the Samba 3.x release series.
The technical exploitation mechanism of this vulnerability involves a carefully crafted symlink attack that allows a local user to manipulate the mountpoint directory file. When the mount.cifs utility processes a CIFS share mounting request, it fails to properly validate whether the specified mountpoint directory is a legitimate target or if it contains symbolic links that could redirect the mounting operation to an arbitrary location. This weakness enables attackers to create symbolic links that point to sensitive system directories or files, thereby allowing them to mount CIFS shares at locations where they would normally not have write permissions. The vulnerability is classified under CWE-367 as a Time-of-Check to Time-of-Use (TOCTOU) flaw, where the system checks for permissions and access rights at one point in time but then uses different access rights at a subsequent point.
The operational impact of CVE-2010-0787 extends beyond simple privilege escalation to potentially enable full system compromise. An attacker exploiting this vulnerability can gain elevated privileges by mounting CIFS shares on directories that would normally require root access to modify, effectively bypassing normal access controls. This capability allows for the creation of malicious file structures, modification of system files, and establishment of persistent access mechanisms. The vulnerability is particularly dangerous in multi-user environments where local users might not have direct administrative access to the system but can leverage this flaw to gain unauthorized privileges. Attackers can use this weakness to establish backdoors, modify critical system components, or escalate their access level to achieve complete system compromise.
Mitigation strategies for this vulnerability require immediate patching of affected Samba versions to the latest available releases that contain the necessary security fixes. System administrators should prioritize updating their Samba installations to versions that address the TOCTOU validation issue in mount.cifs operations. Additionally, implementing proper directory permission controls and monitoring for unauthorized symbolic link creation can provide defense-in-depth measures. The vulnerability aligns with ATT&CK technique T1068 which covers 'Exploitation for Privilege Escalation' and T1548.001 which covers 'Abuse Elevation Control Mechanism'. Organizations should also consider implementing network segmentation and access control policies to limit local user capabilities and reduce the attack surface for such privilege escalation techniques. Regular security audits and vulnerability assessments should be conducted to identify and remediate similar weaknesses in other system components that may present similar TOCTOU attack patterns.