Security readout for executives and security teams
Plain-English summary
This is a Roundcube webmail XSS flaw. A crafted link in a plain-text email can trigger script execution when a user interacts with the message. The CVSS score is medium, but CISA KEV listing means real-world exploitation is reported and exposed webmail needs prompt attention.
Executive priority
Treat as high priority despite medium CVSS because CISA lists it as known exploited. Patch exposed Roundcube quickly and verify completion, particularly for organizations using webmail for sensitive communications.
Technical view
Roundcube before 1.4.14, 1.5.x before 1.5.4, and 1.6.x before 1.6.3 mishandles link replacement in program/lib/Roundcube/rcube_string_replacer.php. The CVSS vector indicates network reachability, low attack complexity, no privileges, required user interaction, changed scope, and low confidentiality/integrity impact.
Likely exposure
Organizations running self-hosted or packaged Roundcube versions below 1.4.14, 1.5.4, or 1.6.3 are exposed, especially where webmail is internet-facing or widely used by staff.
Exploitation context
Active exploitation is supported by CISA’s Known Exploited Vulnerabilities catalog. The provided sources do not describe exploit volume, targets, or a complete attacker playbook.
Researcher notes
Evidence supports a stored or interaction-driven XSS path through crafted links in text/plain messages. Sources identify the vulnerable component and fixed releases, but do not provide detailed exploitation prevalence or post-exploitation outcomes.
Mitigation direction
- Upgrade Roundcube to 1.4.14, 1.5.4, 1.6.3, or later supported releases.
- Apply Debian LTS security updates where Roundcube is installed from Debian packages.
- Check Roundcube and distribution vendor guidance for any environment-specific hardening steps.
- Prioritize internet-facing webmail and high-risk user populations first.
- Review whether vulnerable Roundcube instances can be temporarily restricted until patched.
Validation and detection
- Inventory Roundcube deployments and record exact application or package versions.
- Confirm patched versions or vendor backported fixes are installed.
- Verify package changelogs or deployment records reference the September 2023 security update.
- Review webmail telemetry for unusual user session activity around suspicious email link interactions.
- Confirm exposed webmail endpoints are covered by vulnerability management tracking.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-79: User-session and phishing behavior lookup
Client-side and session-facing weaknesses should be reviewed alongside initial-access and user-execution behaviors. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2023-43770 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Medium
- CVSS
- 6.1 (3.1)
- Known Exploited
- Yes
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CISA KEV status
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N2.82.7Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
6.1MediumVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/roundcube/roundcubemail/commit/e92ec206a886461245e1672d8530cc93c618a49bCVE reference
- https://roundcube.net/news/2023/09/15/security-update-1.6.3-releasedCVE reference
- [debian-lts-announce] 20230922 [SECURITY] [DLA 3577-1] roundcube security updateCVE reference · mailing-list
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-43770CVE reference · government-resource
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.