Security readout for executives and security teams
Plain-English summary
This affects HCL Notes clients with embedded Sametime chat versions 11.0 through 11.0.1 FP4. A logged-in chat user could send a malformed chat message that may run code on another user’s client when chat content is processed. Business impact is targeted workstation compromise, but the issue requires an authenticated sender and user interaction.
Executive priority
Prioritize remediation for environments that still run the affected HCL Notes and Sametime combination, especially where chat users include contractors or broad internal populations. The risk is not KEV-backed or unauthenticated, but remote code execution on user workstations warrants planned patching and temporary access controls.
Technical view
The CVE describes improper input handling (CWE-20) in Sametime chat embedded in HCL Notes. A specially formatted chat message containing JavaScript could trigger remote code execution on another chat client, with the title indicating group chats may load script on restart. CVSS 3.1 is 4.6: network reachable, low complexity, low privileges, and user interaction required.
Likely exposure
Exposure is limited to organizations using HCL Notes 11.0 through 11.0.1 FP4 with the embedded Sametime chat client enabled. Systems not using those versions or not using the affected embedded chat feature are not evidenced as exposed by the source bundle.
Exploitation context
The source bundle does not report active exploitation, and the CVE is not listed as KEV. Exploitation requires an authenticated Sametime chat user and some victim-side interaction or restart-related processing. Treat this as a targeted internal or trusted-user risk rather than an internet-wide unauthenticated threat.
Researcher notes
Evidence is limited to the CVE description, CVSS vector, affected version range, CWE-20, and HCL advisory link. Do not assume exploit availability, fixed versions, or specific mitigations beyond vendor guidance. The restart/group-chat detail comes from the provided title and should be validated against HCL KB0097670.
Mitigation direction
- Inventory HCL Notes clients and identify versions 11.0 through 11.0.1 FP4.
- Review HCL KB0097670 for the vendor’s supported remediation or upgrade guidance.
- Restrict or disable embedded Sametime chat where business impact is acceptable.
- Limit Sametime access to trusted, authenticated users while remediation is pending.
- Educate users to report unexpected chat behavior or crashes.
Validation and detection
- Confirm whether affected HCL Notes versions exist in endpoint inventory.
- Verify whether embedded Sametime chat is enabled on those clients.
- Check HCL advisory status before declaring a client remediated.
- Review endpoint telemetry for suspicious Notes or Sametime child-process behavior.
- Track remediation evidence by client version and deployment group.
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 lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-27760 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
- 4.6 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:N/A:L
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:L/UI:R/S:U/C:L/I:N/A:L2.12.5Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
4.6MediumVector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:N/A:L
Source materials
- CVE List V5 sourceCVE List V5
- https://support.hcltechsw.com/csm?id=kb_article&sysparm_article=KB0097670CVE 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.