CVE-2026-49339 is a high-severity (CVSS 7.1) Path Traversal vulnerability in go.senan.xyz/gonic. O3 Security confirms whether CVE-2026-49339 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Path traversal in getPlaylist/deletePlaylist bypasses ownership check: any authenticated user can read or delete any other user's playlist
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-49339.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-49339 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 358,265 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
go.senan.xyz/gonicReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
gonic is a music streaming server / free-software subsonic server API implementation. The maintainer's fix in commit 6dd71e6a3c966867ef8c900d359a7df75789f410 added an ownership check based on playlist.UserID. However, playlist.UserID is derived from the first path segment of the attacker-controlled playlist ID, with no path containment on the resolved file path. Any authenticated Subsonic user can therefore bypass the ownership check and read any other user's playlist, delete any other user's playlist, and probe arbitrary file paths on the host for existence/readability. This is a bypass of the boundary the 6dd71e6 fix is trying to enforce; it is closely related to the original GONIC-1 IDOR but uses a different primitive (path traversal in the id parameter rather than direct cross-user access). Commit 0824bed88f6bbc490ba28bf09d28e5dfeb07b445 in version 0.21.0 fixes the issue.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | go.senan.xyz/gonic | all versions | 0.21.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for go.senan.xyz/gonic. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update go.senan.xyz/gonic to 0.21.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-49339 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-49339 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-49339. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-49339 in your dependencies?
O3 detects CVE-2026-49339 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.