Security readout for executives and security teams
Plain-English summary
SEPPmail 11.1.10 can reflect a recipient address into HTML without proper attribute encoding, creating a cross-site scripting risk. A successful attack could let an attacker influence what a user sees or does in the SEPPmail web context. The CVE rates this medium severity, not a platform-wide compromise.
Executive priority
Treat as a moderate-priority remediation item. It is not documented as actively exploited here, but mail security infrastructure is sensitive and should be kept on supported, corrected versions.
Technical view
CVE-2021-31739 is a CWE-79 XSS issue in SEPPmail 11.1.10. The CVSS 3.1 vector is AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N, meaning network reachability, low attack complexity, no privileges, required user interaction, changed scope, and low confidentiality/integrity impact.
Likely exposure
Exposure is most likely for organizations running SEPPmail 11.1.10, especially where user-facing SEPPmail workflows process recipient addresses. The source bundle does not provide CPEs or a broader affected-version range.
Exploitation context
The provided sources do not show CISA KEV listing or active exploitation. Exploitation requires user interaction and depends on vulnerable recipient-address handling being reachable in the SEPPmail environment.
Researcher notes
The evidence identifies XSS via recipient address in SEPPmail 11.1.10, but affected CPEs, full version range, and named fix are not included in the bundle. Validate against vendor materials before expanding scope.
Mitigation direction
- Check SEPPmail vendor guidance and release notes for fixed versions.
- Upgrade affected SEPPmail 11.1.10 systems when a vendor-supported fix is confirmed.
- Restrict access to SEPPmail web interfaces where operationally feasible.
- Monitor vendor advisories for affected-version and remediation clarification.
Validation and detection
- Inventory SEPPmail deployments and identify exact running versions.
- Confirm whether SEPPmail 11.1.10 is present in production or externally reachable environments.
- Review vendor advisory details for the affected recipient-address workflow.
- Check logs and support tickets for suspicious recipient-address handling or XSS reports.
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-2021-31739 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
- No
- 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.
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://www.pentagrid.ch/en/blog/multiple-vulnerabilities-in-seppmail/CVE reference
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.