Path Traversal in go.senan.xyz/gonic (CVE-2026-49340)
Summary
Path traversal in go.senan.xyz/gonic (CVE-2026-49340). Data can be tampered with by attackers. Exploitable via ServeCreateOrUpdatePlaylist. Mitigation: upgrade to 0.21.0 or later.
Original description
The description as published by the source.
Summary
A logic error in ServeCreateOrUpdatePlaylist allows any authenticated Subsonic user (including non-admin) to write playlist M3U content to an attacker-controlled absolute filesystem path on the gonic host, and to create intermediate directories with 0o777 permissions.
The bug is independent of the playlist ownership IDOR fixed in 6dd71e6: it is an unreachable guard clause combined with no path containment in Store.Write.
Root cause — unreachable guard clause
server/ctrlsubsonic/handlers_playlist.go:74-90:
func (c *Controller) ServeCreateOrUpdatePlaylist(r *http.Request) *spec.Response {
user := r.Context().Value(CtxUser).(*db.User)
params := r.Context().Value(CtxParams).(params.Params)
playlistID, _ := params.GetFirstID("id", "playlistId")
playlistPath := playlistIDDecode(playlistID) // attacker-controlled, base64-decoded
var playlist playlistp.Playlist
if playlistPath != "" {
if pl, err := c.playlistStore.Read(playlistPath); err != nil && pl != nil {
// ^^^^^^^^^^^^^^^^^^^^^^^^^
// this condition is UNREACHABLE
playlist = *pl
}
}
if playlist.UserID != 0 && playlist.UserID != user.ID {
return spec.NewError(50, "you aren't allowed update that user's playlist")
}
...
`playlist.Store.Re…
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-49340 has been found in go.senan.xyz/gonic.
Attackers can target a specific entry point like ServeCreateOrUpdatePlaylist over the network to misuse the product.
Data can be tampered with by attackers. CVSS score: 8.1/10.
What to do: upgrade go.senan.xyz/gonic to 0.21.0 or later.
If unsure, ask your IT team or search "go.senan.xyz/gonic CVE-2026-49340" on the vendor's site.
CVE-2026-49340 (go.senan.xyz/gonic) — CWE-22 / CVSS v3 8.1
Attack vector: remote (network-reachable) / no user interaction
Attack surface: ServeCreateOrUpdatePlaylist / Store.Write / playlist.Store.Read / playlist
Patched: 0.21.0 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Path traversal (CWE-22) exists in go.senan.xyz/gonic. Attackers reach the vulnerable code path via ServeCreateOrUpdatePlaylist.
Check the vendor advisory for the affected versions of go.senan.xyz/gonic. Attack surface: ServeCreateOrUpdatePlaylist / Store.Write / playlist.Store.Read / playlist.
Severity: High (CVSS 8.1/10). Data can be tampered with by attackers.
Update to 0.21.0.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'go.senan.xyz/gonic' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'go.senan.xyz/gonic' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
go.senan.xyz/gonicを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade go.senan.xyz/gonic to 0.21.0ステージング環境で 0.21.0 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- advisory nvd.nist.gov
- package github.com
- web github.com
- web github.com