CVE-2025-6140 is a medium-severity vulnerability affecting the spdlog library versions up to 1.15.1, specifically in the function scoped_padder located in include/spdlog/pattern_formatter-inl.h. The vulnerability is characterized by resource consumption caused by improper handling within this function. An attacker with local access and low privileges can exploit this flaw without requiring user interaction or elevated permissions. The vulnerability does not impact confidentiality, integrity, or availability directly but can lead to resource exhaustion, potentially degrading system performance or causing denial of service conditions on affected hosts. The vulnerability has been publicly disclosed, and a patch has been released in version 1.15.2, identified by commit 10320184df1eb4638e253a34b1eb44ce78954094. The CVSS 4.0 vector (AV:L/AC:L/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P) reflects a local attack vector with low complexity, no user interaction, and limited impact confined to resource availability. Exploitation requires local access, which limits the attack surface but still poses a risk in environments where untrusted users or processes have access to systems running vulnerable spdlog versions. Since spdlog is a widely used C++ logging library integrated into many applications and systems, the vulnerability could affect a broad range of software products, especially those deployed in enterprise and industrial environments. The vulnerability is not known to be exploited in the wild yet, but public disclosure increases the risk of exploitation attempts. Upgrading to spdlog version 1.15.2 is the recommended remediation to mitigate this issue.

For European organizations, the primary impact of CVE-2025-6140 lies in potential resource exhaustion on systems running vulnerable versions of spdlog. This could lead to degraded application performance or denial of service conditions, particularly in critical infrastructure, industrial control systems, or enterprise environments where spdlog is embedded in logging components. Although the vulnerability requires local access and low privileges, insider threats or compromised internal accounts could exploit this to disrupt services. The impact on confidentiality and integrity is negligible, but availability degradation could affect business continuity, especially in sectors relying on real-time data processing and logging. Organizations with extensive use of C++ applications incorporating spdlog, such as manufacturing, telecommunications, and financial services, may face operational risks if unpatched. Given the medium severity and local attack vector, the threat is more relevant in environments with less stringent internal access controls or where multi-tenant systems share resources. The public disclosure and availability of a patch facilitate timely mitigation but also increase the urgency for organizations to assess and update affected components to prevent exploitation.

1. Immediate upgrade of spdlog to version 1.15.2 or later in all affected applications and systems to apply the official patch addressing the vulnerability. 2. Conduct an inventory of all software products and internal applications that embed spdlog to identify vulnerable versions. 3. Implement strict local access controls and monitoring to limit the ability of unprivileged users to execute code or trigger logging functions that could exploit this vulnerability. 4. Employ resource usage monitoring and alerting on critical systems to detect unusual spikes in CPU or memory consumption that may indicate exploitation attempts. 5. For environments where immediate upgrade is not feasible, consider applying runtime mitigations such as sandboxing or limiting logging verbosity to reduce the attack surface. 6. Integrate this vulnerability into internal vulnerability management and patching workflows to ensure timely remediation. 7. Educate developers and system administrators about the risks associated with local resource exhaustion vulnerabilities and encourage secure coding and deployment practices around logging libraries.