Security readout for executives and security teams
Plain-English summary
CVE-2021-27703 is a cross-site scripting issue reported in the firmware update page of the Sercomm/Etisalat S3-AC2100 router. An authenticated user could be involved in an interaction that lets attacker-controlled script run in a browser context. The public record does not name a vendor fix or broad exploitation.
Executive priority
Treat this as a moderate router administration risk. Prioritize internet-exposed or shared-admin devices first, but do not escalate as an active exploitation emergency based on the supplied evidence.
Technical view
The CVE maps to CWE-79 with CVSS 3.1 score 6.1: network reachable, low complexity, low privileges required, user interaction required, changed scope, and low confidentiality and integrity impact. The supplied affected CPE data is incomplete, but the description names Sercomm Model Etisalat Model S3-AC2100.
Likely exposure
Exposure is most likely where Sercomm/Etisalat S3-AC2100 router administration pages are reachable by users with router credentials, especially if remote management is enabled or admin access is broadly shared.
Exploitation context
No CISA KEV entry is cited, and the bundle does not establish active exploitation. A public GitHub reference is listed, but the provided sources do not prove weaponized use, patch availability, or affected firmware versions.
Researcher notes
Key gaps are affected firmware versions, patch status, and independent exploit telemetry. Validation should focus on asset identification and management-interface exposure, without relying on the incomplete CPE fields in the CVE bundle.
Mitigation direction
- Check Sercomm or Etisalat guidance for firmware updates or advisories.
- Restrict router administration access to trusted management networks only.
- Disable remote administration if it is not operationally required.
- Limit router admin credentials to necessary personnel.
- Replace unsupported devices if no vendor remediation is available.
Validation and detection
- Inventory environments for Sercomm/Etisalat S3-AC2100 devices.
- Confirm whether the firmware update page is accessible to non-admin networks.
- Review whether remote management is enabled on affected routers.
- Check vendor or ISP support channels for fixed firmware details.
- Document firmware versions because the CVE source lacks version granularity.
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-2021-27703 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:L/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:L/UI:R/S:C/C:L/I:L/A:N2.32.7Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
6.1MediumVector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/Mrnmap/mrnmap-cve/blob/main/CVE-2021-27703CVE 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.
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.