Seerr: Path traversal to RCE via /avatarproxy image cache filename from upstream ETag

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-73291
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-12 15:18:33 UTC
Updated2026-08-12 15:18:33 UTC
DescriptionSeerr is an open-source media request and discovery manager for Jellyfin, Plex, and Emby. Prior to version 3.4.0, Seerr's ImageProxy in server/lib/imageproxy.ts uses the upstream ETag and Content-Type response headers to build a cache filename for the unauthenticated GET /avatarproxy/:jellyfinUserId route, allowing a malicious or compromised Jellyfin or Emby server, or a man-in-the-middle attacker on a plaintext media-server connection, to supply traversal sequences that path.join and fs.writeFile normalize outside the cache directory, overwrite /app/dist/index.js or other files, and execute code as the node user after a container restart. This issue is fixed in version 3.4.0.

Risk And Classification

Primary CVSS: v3.1 7.1 HIGH from [email protected]

CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:H

Problem Types: CWE-22 | CWE-94 | CWE-22 CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') | CWE-94 CWE-94: Improper Control of Generation of Code ('Code Injection')

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary7.1HIGHCVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:H
3.1CNADECLARED7.1HIGHCVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Adjacent
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
High
Availability
High

CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Seerr-team Seerr affected < 3.4.0 Not specified

References

ReferenceSourceLinkTags
github.com/seerr-team/seerr/security/advisories/GHSA-mc6w-69r3-62h8 [email protected] github.com
github.com/seerr-team/seerr/releases/tag/v3.4.0 [email protected] github.com
github.com/seerr-team/seerr/commit/f484791105bd81bd5404e01410431ee6fe5769c2 [email protected] github.com
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