CVE-2021-21402Public exploitNetwork attack vector

Unauthenticated file read via legacy endpoint path traversal

Published Mar 23, 2021 · Updated Aug 3, 2024

Path traversal in Jellyfin before 10.7.1 allows remote attackers to read arbitrary server files through unauthenticated HTTP requests. Legacy HLS handlers combine attacker-controlled route segments with request-derived extensions and the transcode path without enforcing containment, while image handlers similarly trust theme or name segments. Encoded Windows path separators enable the documented traversal, and disclosure is limited to files readable by the Jellyfin server process.

CVSS severity7.7
High
EPSS probability80.31%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Path traversal in Jellyfin before 10.7.1 allows remote attackers to read arbitrary server files through unauthenticated HTTP requests. Legacy HLS handlers combine attacker-controlled route segments with request-derived extensions and the transcode path without enforcing containment, while image handlers similarly trust theme or name segments. Encoded Windows path separators enable the documented traversal, and disclosure is limited to files readable by the Jellyfin server process.

The record

CVE
CVE-2021-21402
Published
Mar 23, 2021
Updated
Aug 3, 2024
Vendor
Jellyfin
Product
Jellyfin
Classifications
CWE-22, T1005
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 23, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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=< 10.7.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Jellyfin · Jellyfinversion=< 10.7.1

Published CVSS scores

7.7GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
4.0NIST NVDAV:N/AC:L/Au:S/C:P/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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
T1005Data from Local System

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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