Security readout for executives and security teams
Plain-English summary
CVE-2026-23887 affects Group-Office, a CRM and groupware application. Certain versions store file names without sufficient sanitization, allowing stored cross-site scripting when a user views or interacts with a crafted filename. Business impact is mainly user-session interference and unintended browser actions within Group-Office, not server takeover based on the available sources.
Executive priority
Treat as a moderate-priority application security update. It is not reported as actively exploited, but it can affect user sessions in a business collaboration system. Patch during the next normal maintenance window, sooner where untrusted users can upload files.
Technical view
Affected versions are Group-Office below 6.8.149 and 25.0.1 through below 25.0.80. The issue is stored XSS caused by unsanitized filenames saved to the database. CVSS 4.0 score is 5.1 with network attack vector, low complexity, low privileges required, and user interaction required. Mapped weaknesses include CWE-20 and CWE-79.
Likely exposure
Exposure is likely limited to organizations running affected Group-Office versions where authenticated users can upload or create files with filenames later viewed inside the application. The advisory states impact is limited to the file-viewing context.
Exploitation context
The source bundle does not indicate known active exploitation, and the CVE is not marked KEV. Exploitation requires a low-privileged actor and user interaction with a crafted filename inside Group-Office. Impact may include actions in the victim’s browser session or session interference.
Researcher notes
Evidence is limited to the CVE record, GitHub advisory, and two fixing commits. The advisory describes stored XSS via filenames and fixed versions, but does not provide broader exploit telemetry. Avoid assuming impact beyond the Group-Office file-viewing context without additional testing.
Mitigation direction
- Upgrade Group-Office 6.8.x to 6.8.149 or later.
- Upgrade Group-Office 25.x to 25.0.80 or later.
- Prioritize systems allowing file uploads by untrusted or low-privileged users.
- Review vendor advisory and linked commits for deployment-specific guidance.
Validation and detection
- Inventory all Group-Office instances and record installed versions.
- Confirm no instance runs below 6.8.149 or 25.0.1 through 25.0.79.
- Review application logs for unusual file upload activity or suspicious filenames.
- Verify upgraded instances include the vendor’s filename sanitization fixes.
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-20: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. 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 lookupCWE-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 lookupDatabase behavior lookup
The CVE wording references database injection or access, so collection and exfiltration review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2026-23887 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
- 5.1 (4.0)
- Known Exploited
- No
- Published
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA: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:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N——Primary CVE scoreVulnerability scoring details
Base CVSS 4.0 score
5.1MediumVector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/Intermesh/groupoffice/security/advisories/GHSA-3gj5-gvvr-g6hpCVE reference · x_refsource_CONFIRM
- https://github.com/Intermesh/groupoffice/commit/3fa40d7edd31fbe33babe07061d5a14ad19ea40fCVE reference · x_refsource_MISC
- https://github.com/Intermesh/groupoffice/commit/ac91b128157bc9c5ea015b6141ce71cd3bbc43f0CVE reference · x_refsource_MISC
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 Input Validation
Improper Input Validation represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
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.