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CVE-2021-25827

Emby Server < 4.7.12.0 is vulnerable to a login bypass attack by setting the X-Forwarded-For...

9.8 Critical

Emby Server < 4.7.12.0 is vulnerable to a login bypass attack by setting the X-Forwarded-For header to a local IP-address.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
High

Exploit likelihood

1.50%Up 1.5 points since Jun 29, 2023
90%50%10%1%

What each source reports

NVD Score used 9.8

Emby Server < 4.7.12.0 is vulnerable to a login bypass attack by setting the X-Forwarded-For header to a local IP-address.

Record
CVE-2021-25827
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-290
Updated
2026-11-02
CVE List No score

Emby Server < 4.7.12.0 is vulnerable to a login bypass attack by setting the X-Forwarded-For header to a local IP-address.

Record
CVE-2021-25827
Updated
2026-11-02
EUVDEUVD-2021-12710 0.0

Emby Server < 4.7.12.0 is vulnerable to a login bypass attack by setting the X-Forwarded-For header to a local IP-address.

Record
EUVD-2021-12710
CVSS
0.0 NoneCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-03
GitHub AdvisoriesGHSA-m4q9-68f2-5wc6 9.8

Emby Server < 4.7.12.0 is vulnerable to a login bypass attack by setting the X-Forwarded-For...

Emby Server < 4.7.12.0 is vulnerable to a login bypass attack by setting the X-Forwarded-For header to a local IP-address.

Record
GHSA-m4q9-68f2-5wc6
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-290
Updated
2026-11-02
OSV 9.8

Emby Server < 4.7.12.0 is vulnerable to a login bypass attack by setting the X-Forwarded-For header to a local IP-address.

Record
CVE-2021-25827
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVCVE-2023-33193 9.1

Emby Server Proxy Header Spoofing Vulnerability

Emby Server is a user-installable home media server which stores and organizes a user's media files of virtually any format and makes them available for viewing at home and abroad on a broad range of client devices. This vulnerability may allow administrative access to an Emby Server system, depending on certain user account settings. By spoofing certain headers which are intended for interoperation with reverse proxy servers, it may be possible to affect the local/non-local network determination to allow logging in without password or to view a list of user accounts which may have no password configured. Impacted are all Emby Server system which are publicly accessible and where the administrator hasn't tightened the account login configuration for administrative users. This issue has been patched in Emby Server Beta version 4.8.31 and Emby Server version 4.7.12.

Record
CVE-2023-33193
CVSS 3.1
9.1 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Weakness
CWE-444
Updated
2026-11-02

Affected products

History

History
RecordedChangedSources
facts
aliasesEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2021-25827 is a critical vulnerability (CVSS 9.8) in Emby, published May 30, 2023. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.50%, the 74th percentile. No source names a fixed version.

References

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