Deserialization in Roundcube Webmail
CVE-2026-35537
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.
Vulnerability class: Insecure Deserialization
Published · last modified .
CVSS v3 metric
CVSS v3 base score 3.7 (Low). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N.
EPSS exploit prediction
EPSS: 0.006 (46.6th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 47th percentile — 46.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.006 · change: +0.001
Affected products
- Roundcube Webmail — versions 0, 1.6.0
Weakness classification (CWE)
References
- roundcube.net/news/2026/03/18/security-updates-1.7-rc5-1.6.14-1.5.14 (Third Party Advisory)
- github.com/roundcube/roundcubemail/releases/tag/1.7-rc5 (Release Notes)
- github.com/roundcube/roundcubemail/commit/6d586cfa4d8a31f7957f7a445aaedd52592a0… (Patch)
- github.com/roundcube/roundcubemail/releases/tag/1.6.14 (Release Notes)
- github.com/roundcube/roundcubemail/commit/a4ead994d2f0ea92e4a1603196a197e0d5df1… (Patch)
- github.com/roundcube/roundcubemail/releases/tag/1.5.14 (Release Notes)
- github.com/roundcube/roundcubemail/commit/618c5428edc69fb088e7ac6c89e506dd39df3 (Patch)
- af854a3a-2127-422b-91ae-364da2661108 (Issue Tracking, Mailing List)
Frequently asked questions
- What is CVE-2026-35537?
- CVE-2026-35537 is a low-severity vulnerability in Roundcube Webmail, classified under Deserialization of Untrusted Data. CVSS score: 3.7/10. Published 2026-04-03.
- How severe is CVE-2026-35537?
- Low severity. CVSS v3 base score is 3.7 out of 10.