Security readout for executives and security teams
Plain-English summary
Emby Server versions before 4.7.12.0 may allow a login bypass when a request claims to come from a local IP address through the X-Forwarded-For header. This matters most for internet-facing or untrusted-network Emby deployments.
Executive priority
Prioritize remediation for any internet-facing or shared-network Emby Server. The business risk is unauthorized media-server access through an authentication bypass, but severity scoring and exploitation evidence are incomplete.
Technical view
The reported issue is an authentication bypass in Emby Server < 4.7.12.0 tied to trust of X-Forwarded-For. A crafted request can present a local IP address in that header, which sources describe as enabling login bypass. CVSS, CWE, and complete affected CPE data are not provided.
Likely exposure
Exposure is likely limited to organizations running Emby Server before 4.7.12.0, especially if reachable by untrusted users or through proxy configurations that pass client-controlled forwarding headers.
Exploitation context
The provided sources do not state active exploitation, and the CVE is not listed as KEV. Public issue and advisory references exist, so defenders should assume technical details may be discoverable without treating exploitation as confirmed.
Researcher notes
The key technical question is whether Emby trusted client-supplied X-Forwarded-For as proof of local origin. Validate version exposure and proxy trust boundaries. Do not infer broader MediaBrowser or unrelated Emby components from the supplied data.
Mitigation direction
- Upgrade Emby Server to 4.7.12.0 or later where applicable.
- Review Emby vendor guidance and the linked GitHub advisory.
- Restrict Emby Server access to trusted networks where possible.
- Ensure proxies do not pass untrusted X-Forwarded-For values.
Validation and detection
- Inventory all Emby Server instances and record versions.
- Confirm no instance runs below 4.7.12.0.
- Review reverse proxy handling of X-Forwarded-For headers.
- Check access logs for unusual local-IP forwarded headers.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CVE-2021-25827 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS and timeline data
No CVSS vectors or timeline events were available in the normalized CVE source material.
Source materials
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.