CVE-2021-28807Public exploitNetwork attack vector

Privileged-session hijack via unsanitized event log

Published Jun 3, 2021 · Updated Sep 16, 2024

Cross-site scripting in QNAP Systems, Inc. Q'center before 1.10.1004 or 1.12.1012 allows remote authenticated users to inject code. The Q'center Event log reflects a failed-login account name controlled by the attacker without sanitization, so script executes when a privileged user opens the event section. The attack requires access to the Q'center interface and interaction by a privileged viewer, enabling session hijacking and related actions available to that session.

CVSS severity7.7
High
EPSS probability1.38%
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 QNAP Systems, Inc. Q'center before 1.10.1004 or 1.12.1012 allows remote authenticated users to inject code. The Q'center Event log reflects a failed-login account name controlled by the attacker without sanitization, so script executes when a privileged user opens the event section. The attack requires access to the Q'center interface and interaction by a privileged viewer, enabling session hijacking and related actions available to that session.

The record

CVE
CVE-2021-28807
Published
Jun 3, 2021
Updated
Sep 16, 2024
Vendor
Linn Products Limited
Product
Q'center
Classifications
CWE-79, T1189
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 3, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=unspecified <v1.10.1004
  2. Affected versionversion=unspecified <v1.12.1012

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Linn Products Limited · Q'centerversion=unspecified <v1.10.1004; version=unspecified <v1.12.1012

Published CVSS scores

3.5NIST NVDAV:N/AC:M/Au:S/C:N/I:P/A:N
5.4NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
7.7QNAP Systems, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/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-79Cross-site Scripting (XSS)
T1189Stored/Reflected XSS

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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