CVE-2025-34324 is a vulnerability in Tinexta InfoCert S.p.A.'s GoSign Desktop software (versions 2.4.0 and earlier) related to improper verification of cryptographic signatures (CWE-347). The software distributes application updates using an update manifest that lists package URLs and SHA-256 hashes but does not digitally sign this manifest. The authenticity of the update manifest depends solely on the security of the TLS channel used to fetch it. However, when a proxy is configured, GoSign Desktop allows disabling TLS certificate validation. This creates a critical security flaw: an attacker capable of intercepting network traffic (e.g., via a man-in-the-middle attack) can supply a malicious update manifest and a corresponding package with a matching SHA-256 hash. Because the manifest is not signed, the client cannot verify the integrity or authenticity beyond the TLS channel, which may be compromised. Consequently, the client may download and install a tampered update, resulting in arbitrary code execution. On Windows and macOS, the attacker gains the privileges of the GoSign Desktop user, while on some Linux deployments, the attacker may achieve elevated privileges. Additionally, a local attacker with the ability to modify proxy settings can exploit this vulnerability to escalate privileges by forcing the installation of a crafted update. The vulnerability has a CVSS 4.0 score of 7, reflecting high severity due to the combination of local privilege requirements, user interaction, and the potential for high impact on confidentiality, integrity, and availability. No patches or exploit code are currently publicly available, and no known exploits are in the wild. This vulnerability highlights the risks of relying solely on TLS for update authenticity without cryptographic signature verification of update manifests, especially when TLS validation can be disabled.

For European organizations, the impact of CVE-2025-34324 can be significant, particularly for those relying on GoSign Desktop for digital signature workflows and document authentication. Successful exploitation can lead to arbitrary code execution on affected endpoints, potentially allowing attackers to compromise sensitive documents, steal credentials, or move laterally within networks. On Windows and macOS, the attacker gains user-level privileges, which may be sufficient to access confidential information or install persistent malware. On Linux systems where elevated privileges can be obtained, the risk escalates to full system compromise. The vulnerability also enables local privilege escalation if an attacker can modify proxy settings, increasing the threat from insider attackers or malware with limited access. Given that GoSign Desktop is used in legal, financial, and governmental sectors for secure document signing, exploitation could undermine trust in digital signatures and disrupt critical business processes. The reliance on TLS without manifest signature verification is particularly risky in environments where network traffic interception is possible, such as public or poorly secured networks. Overall, this vulnerability threatens confidentiality, integrity, and availability of systems and data, with potential regulatory and reputational consequences under European data protection laws.

European organizations should take immediate steps to mitigate this vulnerability beyond generic advice: 1) Disable use of proxies that allow disabling TLS certificate validation for GoSign Desktop or enforce strict TLS validation policies at the network level. 2) Monitor and restrict local user permissions to prevent unauthorized modification of proxy settings, especially on Linux systems. 3) Implement network security controls such as TLS interception detection and man-in-the-middle attack prevention to protect update channels. 4) Where possible, isolate GoSign Desktop update traffic to trusted network segments or VPNs to reduce interception risk. 5) Conduct endpoint monitoring for unusual update activity or unexpected process executions related to GoSign Desktop. 6) Engage with Tinexta InfoCert S.p.A. to obtain patches or updates that introduce cryptographic signature verification of update manifests. 7) Educate users about the risks of configuring proxies that disable TLS validation and the importance of applying updates only from trusted sources. 8) Consider application whitelisting or code integrity policies to prevent execution of unauthorized binaries. 9) Regularly audit and review proxy configurations and network security policies to ensure compliance with best practices. 10) Prepare incident response plans specifically addressing potential compromise via malicious updates to enable rapid containment.