CVE-2026-35539: Roundcube Webmail · XSS or 'Cross-site Scripting'
Affects Roundcube WebmailSource CVE Database V5
Not known to be exploited · CVSS 6.1 Medium : upgrade to 1.6.14 or 1.5.14 when convenient.
Data as of 30 Oct 2026, 11:52 UTC
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 16% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 1.6.14, 1.5.14
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:NExploitation evidence
Disclosed: evidence found.
CVE published 3 Apr 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.
What to do
Upgrade Webmail and roundcube/roundcubemail to 1.6.14 or 1.5.14.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| RoundcubeWebmail | Affected
| Fixed in
|
| RoundcubeWebmail | Affected
| Fixed in
|
GitHubroundcube/roundcubemailpkg:github/roundcube/roundcubemailOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
If you cannot patch yet, users should exercise caution when previewing HTML attachments and consider disabling attachment preview functionality if feasible.
Description
CVE-2026-35539 is a medium severity cross-site scripting (XSS) vulnerability in Roundcube Webmail versions before 1.5.14 and 1.6.14. The issue arises from insufficient sanitization of HTML attachments in preview mode, allowing an attacker to execute script code if a victim previews a crafted text/html attachment. This vulnerability requires user interaction to exploit and impacts confidentiality and integrity but not availability.
References
- roundcube.net/news/2026/03/18/security-updates-1.7-rc5-1.6.14-1.5.14 (opens in a new tab)
- github.com/roundcube/roundcubemail/releases/tag/1.7-rc5 (opens in a new tab)
- github.com/roundcube/roundcubemail/commit/1b30edf5369668c92fe91dae3d52e477c808aa4f (opens in a new tab)
- github.com/roundcube/roundcubemail/releases/tag/1.6.14 (opens in a new tab)
- github.com/roundcube/roundcubemail/commit/10a6d1fa8acac85c727b0a6ae4a6642bfa27bea1 (opens in a new tab)
- github.com/roundcube/roundcubemail/releases/tag/1.5.14 (opens in a new tab)
- github.com/roundcube/roundcubemail/commit/d742954ccbcdee7020f8f2e7c49ce0fca5a0efab (opens in a new tab)