CVE-2026-3091
Synology Presto Client ≤ 2.1.3-0672
Raw vector
CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:HSummary
CVE-2026-3091 is a medium-severity Uncontrolled Search Path Element (CWE-427) vulnerability in Synology Presto Client. Its CVSS base score is 6.7 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Path Interception (T1034); ranked at the 4th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to CM-6 (Configuration Settings) and AC-3 (Access Enforcement) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-3091 is an uncontrolled search path element vulnerability (CWE-427) in Synology Presto Client versions before 2.1.3-0672. The issue arises during installation, where the software fails to properly validate DLL loading paths, allowing a malicious DLL placed in advance in the same directory as the installer to be executed instead of the legitimate one.
Local users with low privileges can exploit this vulnerability by placing a malicious DLL in the installer's directory prior to installation. Exploitation requires high attack complexity, local access, and user interaction, such as initiating the installer, per the CVSS v3.1 vector AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H (base score 6.7). Successful attacks enable reading or writing arbitrary files, potentially leading to full system compromise through escalated privileges or persistence.
Synology's security advisory (Synology_SA_26_02), available at https://www.synology.com/en-global/security/advisory/Synology_SA_26_02, details mitigation steps and patches for this vulnerability.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-7405
Vulnerability Data
An uncontrolled search path element vulnerability in Synology Presto Client before 2.1.3-0672 allows local users to read or write arbitrary files and conduct denial-of-service during installation by placing a malicious DLL in advance in the same directory as the installer.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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- 2 hardening rules · 1 OS baseline
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Mitigating Controls (NIST 800-53 r5) AI
Establishes restrictive configuration settings that can define and lock down approved search paths.
Enforces approved authorizations so that only intended actors can place or modify elements in the search path.
Limits privileges so unintended actors cannot write to or control directories in the product's search path.
Restricts logical and physical access to change system configuration, including search-path settings and directories.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure-development practices directly address design of search paths and resource loading.
Hardened configuration baselines can enforce safe search-path settings and reduce exposure.
Execution allow-listing can block malicious binaries placed in hijackable search locations.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing can detect uncontrolled search-path issues but does not prevent them by itself.
Restricting software installation reduces the chance that an attacker-controlled path element is introduced into the search path.
Secure system architecture and engineering principles require explicit control over search paths and resource locations.
Secure coding practices directly address the use of fixed or controlled search paths that can be influenced by unintended actors.
Configuration management can enforce approved search-path settings but does not inherently prevent the weakness.
Hardening callouts derived
Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).
Oracle Linux 8 (1 rule)
- V-248577 OL 8 must enable kernel parameters to enforce Discretionary Access Control (DAC) on symlinks. prevents CWE-427