CVE-2021-25828Public exploitNetwork attack vector

Browser script execution via reflected web path

Published Jun 28, 2023 · Updated Dec 5, 2024

Reflected XSS in Emby Server before 4.6.0.50 allows remote attackers to execute script in a user's browser through a crafted /web/ URL. The server reflects everything after /web/ from the request path into the returned page without neutralizing script markup, causing browser-interpreted input to run as code. Exploitation requires a user to open an attacker-crafted URL for a reachable server; the resulting script executes in that user's Emby web origin.

CVSS severity6.1
Medium
EPSS probability0.53%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reflected XSS in Emby Server before 4.6.0.50 allows remote attackers to execute script in a user's browser through a crafted /web/ URL. The server reflects everything after /web/ from the request path into the returned page without neutralizing script markup, causing browser-interpreted input to run as code. Exploitation requires a user to open an attacker-crafted URL for a reachable server; the resulting script executes in that user's Emby web origin.

The record

CVE
CVE-2021-25828
Published
Jun 28, 2023
Updated
Dec 5, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-79, T1204.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 28, 2023CVE publishedPublication date reported by the CVE source.
  2. Dec 5, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/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.

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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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1204.001Malicious Link

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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