CVE-2023-5631
XSS in Roundcube Webmail ≤ 1.4.15
Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:NCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2023-5631 is a medium-severity Cross-site Scripting (CWE-79) vulnerability in Roundcube Webmail. Its CVSS base score is 6.1 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Protocol or Service Impersonation (T1001.003); ranked in the top 0.5% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog; a public proof-of-concept is referenced.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
Roundcube webmail before version 1.4.15, 1.5.x before 1.5.5, and 1.6.x before 1.6.4 is affected by a stored cross-site scripting flaw tracked as CVE-2023-5631. The issue resides in the HTML sanitization logic of program/lib/Roundcube/rcube_washtml.php, which fails to properly neutralize a crafted SVG document embedded in an HTML email message and thereby permits arbitrary JavaScript execution.
A remote attacker can exploit the vulnerability by sending a victim a malicious HTML email containing the crafted SVG. When the recipient views the message through the Roundcube interface, the injected script runs in the application context with the victim’s privileges, enabling actions such as cookie theft or mailbox manipulation under the CVSS vector AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.
Public advisories and the referenced Roundcube commit direct administrators to upgrade to the fixed releases 1.4.15, 1.5.5, or 1.6.4; distribution trackers such as the Debian bug report and oss-security postings likewise emphasize applying these updates as the primary mitigation.
The associated EPSS score has reached a peak of 0.8520 with a current value of 0.8324, indicating sustained exploitation interest after disclosure.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2023-57924
Vulnerability Data
Roundcube before 1.4.15, 1.5.x before 1.5.5, and 1.6.x before 1.6.4 allows stored XSS via an HTML e-mail message with a crafted SVG document because of program/lib/Roundcube/rcube_washtml.php behavior. This could allow a remote attacker to load arbitrary JavaScript code.
- CWE(s)
- KEV Date Added
- 26 October 2023
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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V1.1.2V1.3.2
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Penetration testing submits XSS payloads to web applications, detecting cross-site scripting flaws for subsequent remediation.
Validates web inputs to reject script-related content that could produce XSS.
Output validation against expected content can reject or sanitize script content in generated web pages, reducing XSS exploitability.
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 SDLC practices directly target introduction of XSS via coding standards/testing (mostly), yet the single broad outcome leaves many specific neutralization vectors unaddressed (partial).
Patching and EOL replacement can remediate known XSS instances in libraries or frameworks (partial) but do nothing to enforce input neutralization in application code (none).
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.
A.5.6 only promotes membership in groups to improve knowledge, receive alerts, and share information; it performs no action that stops XSS exploitation (or even the underlying neutralization defect) and is a pure dependency for other controls per the owner's labeling rule.