Raw vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:NSummary
CVE-2026-35537 is a low-severity Deserialization of Untrusted Data (CWE-502) vulnerability in Roundcube Webmail. Its CVSS base score is 3.7 (Low).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 39th 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 SA-11 (Developer Testing and Evaluation) and SI-10 (Information Input Validation) — 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-2026-35537 is an unsafe deserialization vulnerability in the redis/memcache session handler of Roundcube Webmail versions prior to 1.5.14 and 1.6.14. This flaw, classified under CWE-502 (Deserialization of Untrusted Data), allows crafted session data to trigger arbitrary file write operations. The vulnerability received a CVSS v3.1 base score of 3.7 (AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N), reflecting low severity due to high attack complexity and limited integrity impact.
Unauthenticated attackers can exploit this issue over the network by supplying specially crafted session data to the affected session handler. Successful exploitation enables arbitrary file writes on the server, potentially leading to further compromise depending on file locations and permissions, though no confidentiality or availability impacts are directly associated.
Mitigation involves upgrading to Roundcube Webmail 1.5.14 or 1.6.14, as detailed in the project's release notes. Relevant patches are available in specific GitHub commits, including 618c5428edc69fb088e7ac6c89e506dd39df3, 6d586cfa4d8a31f7957f7a445aaedd52592a0e74, and a4ead994d2f0ea92e4a1603196a197e0d5df1620.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-18575
Vulnerability Data
An issue was discovered in Roundcube Webmail before 1.5.14 and 1.6.14. Unsafe deserialization in the redis/memcache session handler may lead to arbitrary file write operations by unauthenticated attackers via crafted session data.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Developer testing and evaluation can uncover deserialization flaws before deployment.
Input validation directly stops deserialization of untrusted data by ensuring inputs are valid before processing.
Engineering principles such as safe deserialization and input sanitization structurally prevent the weakness from being introduced.
Integrity verification tools can detect malformed or tampered serialized data after the fact.
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.
PR.PS-02 addresses only post-deployment updates/patching and cannot prevent introduction of unsafe deserialization code, yet it can remediate some instances when the flaw exists in outdated libraries or components.
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 includes validation of deserialization routines and the use of untrusted data, reducing the likelihood that unsafe object reconstruction will be deployed.
Requiring vetted libraries, regular updates and SAST before release reduces the likelihood that deserialization logic will accept and act on attacker-controlled serialized objects.
Regular scanning of third-party libraries and timely patching reduce the likelihood that unsafe deserialization vulnerabilities remain active.
Mandatory malware scanning of data received over networks or storage media intercepts malicious serialized payloads before they are deserialized by the target application.