CVE-2026-79779 — rclone
Fix: rclone/rclone@59b513bCVE-2026-79779 is a CWE-319 vulnerability in github.com/rclone/rclone. A fix is available for github.com/rclone/rclone — see the affected versions and patch details below.
rclone before v1.75.0 WebDAV Credential Exposure via HTTPS-to-HTTP Redirect
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 CVE-2026-79779.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
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
1. Summary
WebDAV's default redirect handling can replay Basic authorization and configured Cookie headers over plaintext HTTP after a same-host HTTPS-to-HTTP redirect. This was reproduced through the real backend. Unlike the low-impact STS token in rclone's published S3 redirect advisory, Basic passwords and session cookies are complete reusable credentials, supporting a High rating when they grant normal WebDAV read/write access.
The credible threat requires a legitimate endpoint, gateway, or accelerator to emit an unsafe redirect and an adjacent/on-path actor to observe the plaintext hop. A report should not rely on a malicious original WebDAV endpoint because that endpoint already receives the credentials.
2. Affected Assets & Attack Surface
- Backend configuration/authentication:
backend/webdav/webdav.go:127-139,170-206,440-530 - Shared redirect callback:
lib/rest/rest.go:218-231 - HTTP client:
fs/fshttp/http.go:311-329 - Credentials: Basic passwords, bearer authorization, SharePoint/session cookies, and configured secret headers
- Confirmed affected version:
<= v1.74.0-240
3. Technical Root Cause Analysis
PreserveMethodRedirectFn limits redirect count and restores the original method, but it does not reject a transport downgrade or compare the full origin tuple. The client therefore relies on Go's hostname-oriented sensitive-header forwarding rules. Those rules can preserve Authorization and Cookie on a same-host redirect even when the new scheme is plaintext HTTP.
4. Proof-of-Concept & Evidence
- Configure the actual WebDAV backend with Basic credentials and a Cookie.
- Have the TLS endpoint return
307 Temporary Redirectto an HTTP listener on the same hostname and a different port. - rclone follows the redirect while preserving the WebDAV method.
- The plaintext listener receives both the Basic
Authorizationvalue and Cookie.
5. Impact Assessment
An on-path observer can reuse the captured password, bearer token, or session cookie for the account's permitted WebDAV operations. Confidentiality, integrity, and availability impact depend on that account's permissions.
6. Remediation Guidance
- Reject every HTTPS-to-HTTP redirect before replay.
- Forward authenticated requests by default only when scheme, hostname, and effective port are unchanged.
- Strip authorization, cookies, proxy credentials, and configured secret headers on all other redirects.
- Put necessary provider exceptions behind exact destination allowlists.
- Cover
301,302,303,307, and308in regression tests.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/rclone/rclone | all versions | 1.75.0go get github.com/rclone/rclone@v1.75.0 |
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, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/rclone/rclone to 1.75.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-79779 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.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
This Moderate impact flaw in rclone allows an on-path attacker to capture credentials by exploiting improper handling of HTTPS-to-HTTP redirects on the same host. This occurs when rclone fails to reject transport downgrades, leading to the replay of Basic authorization and Cookie headers over plaintext HTTP.…
Until packages are updated, avoid using rclone WebDAV remotes against servers or gateways that issue HTTPS-to-HTTP redirects. Prefer remotes that remain on HTTPS for the full request path, and do not send Basic authentication or session cookies through intermediaries that can downgrade the TLS connection.Source: Red Hat security advisory for CVE-2026-79779 (CC BY 4.0)
Frequently Asked Questions
Is CVE-2026-79779 in your dependencies?
Find it across Go, including transitive dependencies.