CVE-2022-31256 is a high-severity vulnerability classified as CWE-59 (Improper Link Resolution Before File Access, also known as 'Link Following') found in the sendmail service of SUSE openSUSE Factory distributions prior to version 8.17.1-1.1. The vulnerability arises from a flaw in a script invoked by the sendmail systemd service, where symbolic links are not properly resolved before file access. This improper handling allows a local attacker with access to the mail user account to exploit the vulnerability to escalate privileges to root. The vulnerability does not require prior authentication or user interaction beyond local access to the mail user account, making it a local privilege escalation vector. The CVSS v3.1 base score is 7.7, reflecting high impact on confidentiality and integrity, with no impact on availability. The attack vector is local (AV:L), attack complexity is low (AC:L), and privileges required are none (PR:N), indicating that any local user with mail privileges can exploit this issue without additional credentials. The vulnerability affects the sendmail component in openSUSE Factory, a rolling release distribution used primarily by developers and advanced users. No known exploits in the wild have been reported as of the publication date. The root cause is the failure to securely handle symbolic links in scripts run by systemd services, which can be manipulated by local users to gain unauthorized root access.

For European organizations using openSUSE Factory with the vulnerable sendmail versions, this vulnerability poses a significant risk of local privilege escalation. An attacker who has local access to a mail user account can leverage this flaw to gain root privileges, potentially leading to full system compromise. This can result in unauthorized access to sensitive data, modification or deletion of critical files, and disruption of mail services. Organizations relying on openSUSE Factory in development, testing, or production environments may face increased risk if local user accounts are not tightly controlled. The vulnerability undermines system integrity and confidentiality, which is critical for compliance with European data protection regulations such as GDPR. Additionally, if compromised systems are part of larger networks, attackers could use root access to pivot and escalate attacks, threatening broader organizational infrastructure.

1. Immediate upgrade: Organizations should upgrade sendmail on openSUSE Factory to version 8.17.1-1.1 or later, where the vulnerability is patched. 2. Restrict local access: Limit local user accounts with mail privileges to trusted personnel only, and enforce strict access controls and monitoring on these accounts. 3. Harden systemd scripts: Review and harden scripts invoked by systemd services to ensure they properly handle symbolic links and do not follow untrusted links. 4. Implement file system protections: Use filesystem permissions and mount options (e.g., noexec, nodev) to reduce the risk of malicious link creation and execution. 5. Monitor logs and audit: Enable detailed logging and auditing of sendmail and systemd service activities to detect suspicious behavior indicative of exploitation attempts. 6. Use Mandatory Access Control (MAC): Employ SELinux or AppArmor policies to restrict sendmail and related scripts from performing unauthorized file operations. 7. Network segmentation: Isolate systems running openSUSE Factory to limit lateral movement in case of compromise.