CVE-2021-27703Public exploitNetwork attack vector

Authenticated script execution via firmware image upload

Published Nov 12, 2024 · Updated Nov 15, 2024

Cross-site scripting in the firmware update page of the Sercomm Etisalat S3-AC2100 allows remote authenticated users to execute script in a browser. The update handler accepts an uploaded .img file containing an HTML event-handler payload and renders that input without neutralization. Exploitation requires access to the firmware-update interface and user interaction; the demonstrated consequence is script execution in the page context, while affected firmware versions remain unpublished.

CVSS severity5.4
Medium
EPSS probability0.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site scripting in the firmware update page of the Sercomm Etisalat S3-AC2100 allows remote authenticated users to execute script in a browser. The update handler accepts an uploaded .img file containing an HTML event-handler payload and renders that input without neutralization. Exploitation requires access to the firmware-update interface and user interaction; the demonstrated consequence is script execution in the page context, while affected firmware versions remain unpublished.

The record

CVE
CVE-2021-27703
Published
Nov 12, 2024
Updated
Nov 15, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Nov 12, 2024CVE publishedPublication date reported by the CVE source.
  2. Nov 15, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.4GitHub Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1059.007JavaScript/JScript

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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