CVE-2021-25827: Emby Server < 4.7.12.0 is vulnerable to a login bypass attack by setting the X-Forwarded-For header to a local

Q: How do I fix CVE-2021-25827?

emby: upgrade to 4.7.12.0. Exact commands for each OS are on this page.

Q: Is CVE-2021-25827 being exploited?

CVE-2021-25827 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-25827 affect?

CVE-2021-25827 affects emby. Severity is critical (CVSS 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.

Q: How urgent is CVE-2021-25827?

Priority 66/100. Critical severity; Public exploit reference; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action

This week

CRITICAL 9.8REMOTEUPGRADE

CVE-2021-25827 is a critical-severity flaw (CVSS 9.8) affecting emby. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

Critical severity
Public exploit reference
CISA SSVC: automatable with total technical impact
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.5% (top 26%)
CISA exploited list	No
Weakness	CWE-290
Published	2023-06-28
Last modified	2026-10-24

Publisher (CNA): MITRE · Vendor: emby

Last updated 2026-10-24 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2023-06-28 20:15 UTCPublished CVE record published
2026-10-24 13:10 UTCUpdated Record last modified

emby emby UPGRADE

Affected: < 4.7.12.0

Fixed in: 4.7.12.0

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy emby || rpm -q emby || emby --version

2. UPGRADE to 4.7.12.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade emby

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade emby

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Exact fixes by distribution

Fedora 46 · gnome-shell-extension-tiling-assistant · FIXED · 56-1.fc46 · FEDORA-2026-ebf66a5321 · source

sudo dnf upgrade --advisory=FEDORA-2026-ebf66a5321

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-25827?

emby: upgrade to 4.7.12.0. Exact commands for each OS are on this page.

Is CVE-2021-25827 being exploited?

CVE-2021-25827 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-25827 affect?

CVE-2021-25827 affects emby. Severity is critical (CVSS 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.

How urgent is CVE-2021-25827?

Priority 66/100. Critical severity; Public exploit reference; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action

Related CVEs

CVE-2021-25828 MEDIUM 6.1 UPGRADE Emby Server versions < 4.6.0.50 is vulnerable to Cross Site Scripting (XSS) vulnerability via a crafted GET re

References

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