CVE-2026-2659 identifies an out-of-bounds read vulnerability in the Squirrel scripting language, versions 3.0 to 3.2, specifically within the SQFuncState::PopTarget function located in the source file sqfuncstate.cpp. The vulnerability is triggered by manipulating the _target_stack argument, causing the function to read memory outside the allocated bounds. This flaw can be exploited by an attacker with local access and limited privileges (PR:L), without requiring user interaction or authentication. The vulnerability does not affect confidentiality, integrity, or availability directly but allows an attacker to read potentially sensitive memory contents, which could lead to information disclosure. The CVSS 4.0 vector indicates a medium severity score of 4.8, reflecting the limited attack surface and impact. The vulnerability was responsibly disclosed early to the Squirrel project, but no patch or response has been issued yet. The exploit code has been publicly disclosed, increasing the risk of local exploitation. Squirrel is often embedded in applications and devices for scripting purposes, so the vulnerability could affect a range of software products that integrate this language interpreter. Since the attack requires local access, remote exploitation is not feasible without additional vulnerabilities or access vectors.

For European organizations, the primary impact of CVE-2026-2659 is the potential for local attackers to gain unauthorized access to sensitive memory contents within applications embedding the vulnerable Squirrel interpreter. This could lead to leakage of confidential information such as cryptographic keys, credentials, or proprietary data. Although the vulnerability does not allow code execution or denial of service directly, information disclosure can facilitate further attacks or privilege escalation. Organizations using Squirrel in embedded systems, industrial control systems, or software development environments may face increased risk if local access controls are weak. The lack of a patch increases exposure duration. The impact is more pronounced in sectors with high security requirements, such as finance, critical infrastructure, and government agencies. However, since exploitation requires local access, the threat is mitigated by strong endpoint security and access controls.

Given the absence of an official patch, European organizations should implement specific mitigations: 1) Restrict local access to systems running vulnerable versions of Squirrel by enforcing strict user permissions and limiting administrative privileges. 2) Employ application whitelisting and endpoint detection to monitor and prevent unauthorized execution of scripts or binaries embedding the vulnerable interpreter. 3) Conduct code audits and inventory to identify all instances of Squirrel usage within internal software and embedded devices. 4) Where feasible, replace or upgrade Squirrel to a non-vulnerable version once available or consider alternative scripting engines. 5) Use memory protection mechanisms such as Address Space Layout Randomization (ASLR) and Data Execution Prevention (DEP) to reduce exploitation success. 6) Monitor for suspicious local activity and anomalous memory access patterns that could indicate exploitation attempts. 7) Engage with vendors or open-source maintainers to expedite patch development and deployment. 8) Implement network segmentation to limit lateral movement from compromised local hosts.