GHSA-66hp-wgxq-6f5q is a medium-severity (CVSS 6.3) Path Traversal vulnerability in github.com/rclone/rclone. O3 Security confirms whether GHSA-66hp-wgxq-6f5q is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
rclone archive/zip: Zip Slip via unsanitized zip entry names lets a malicious archive escape its own namespace
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-66hp-wgxq-6f5q.
Real-World Exposure
github.com/rclone/rcloneReal-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
Summary
backend/archive mounts a zip file as a browsable, syncable rclone Fs (e.g. rclone lsf :zip:downloaded.zip or rclone copy :zip:downloaded.zip dest:). Go's archive/zip package does not sanitize file.Name - it is taken verbatim from the untrusted zip's central directory. readZip() in backend/archive/zip/zip.go applies path.Clean to the entry name, but this alone cannot fully neutralize a name with more .. components than real segments preceding them (e.g. "../../etc/cron.d/evil" stays exactly as-is after cleaning). When the archive is mounted with an empty root (the common case), there was no check at all that the resulting name stayed inside the archive's own namespace, so it was stored verbatim and returned unchanged by Object.Remote().
fs/sync/fs/operations use srcObj.Remote() directly as the destination-relative path when copying between filesystems, so a maliciously crafted zip file can cause rclone copy/sync to attempt writes outside the intended destination directory on whatever backend it targets - this is the well-known "Zip Slip" vulnerability class (https://security.snyk.io/research/zip-slip-vulnerability) applied to rclone's own zip-mounting backend. It is distinct from cmd/archive/extract, which already validates via its own destPath() choke point and is not affected.
Details
Vulnerable code (before fix), backend/archive/zip/zip.go, (*Fs).readZip:
for _, file := range zr.File {
remote := strings.Trim(path.Clean(file.Name), "/")
if remote == "." { remote = "" }
remote = path.Join(f.prefix, remote)
if f.root != "" {
// Ignore all files outside the root
if !strings.HasPrefix(remote, f.root) { continue }
...
}
...
o := &Object{f: f, remote: remote, ...}
dt.Add(o)
}
The escape check only ran when f.root != "", and even then used a bare strings.HasPrefix with no boundary check (so f.root="foo" incorrectly also matched a sibling entry "foobar").
PoC
Built a zip in memory with Go's real archive/zip writer (entry name "../../etc/cron.d/evil", not sanitized by the writer either), wrote it to disk, and mounted it via the actual production constructor zip.New(ctx, localFs, "evil.zip", "", ""):
zip entry Name="../../etc/cron.d/evil" -> Object.Remote()="../../etc/cron.d/evil"
Fully outside the archive's own namespace - confirmed via a regression test that mounts the malicious zip through the real local backend and inspects the resulting Fs's internal dirtree and every Object's Remote().
Impact
A user who runs rclone copy/sync/mount against an untrusted zip file (downloaded, e-mailed, etc.) can have files written outside the intended destination directory on the destination backend, depending on that backend's own confinement. No server compromise or custom remote configuration is required from the attacker - only a crafted zip file and a normal rclone copy/sync invocation by the victim.
Fix
Skip any zip entry whose cleaned+prefixed name still escapes the archive's own namespace, rather than exposing it. Also tightened the pre-existing root filter's weak prefix check.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/rclone/rclone | ≥ 1.72.0&&< 1.75.1 | 1.75.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/rclone/rclone. 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 github.com/rclone/rclone to 1.75.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-66hp-wgxq-6f5q 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 GHSA-66hp-wgxq-6f5q 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 GHSA-66hp-wgxq-6f5q. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-66hp-wgxq-6f5q in your dependencies?
O3 detects GHSA-66hp-wgxq-6f5q across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.