{"id":"CVE-2026-79779","aliases":["BIT-rclone-2026-79779","GHSA-h4mf-4v27-hggj","GO-2026-6197"],"url":"https://o3.security/vulnerability/CVE-2026-79779","summary":"rclone before v1.75.0 WebDAV Credential Exposure via HTTPS-to-HTTP Redirect","details":"## 1. Summary\n\nWebDAV'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.\n\nThe 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.\n\n## 2. Affected Assets & Attack Surface\n\n- Backend configuration/authentication: `backend/webdav/webdav.go:127-139`, `170-206`, `440-530`\n- Shared redirect callback: `lib/rest/rest.go:218-231`\n- HTTP client: `fs/fshttp/http.go:311-329`\n- Credentials: Basic passwords, bearer authorization, SharePoint/session cookies, and configured secret headers\n- Confirmed affected version: `<= v1.74.0-240`\n\n## 3. Technical Root Cause Analysis\n\n`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.\n\n## 4. Proof-of-Concept & Evidence\n\n1. Configure the actual WebDAV backend with Basic credentials and a Cookie.\n2. Have the TLS endpoint return `307 Temporary Redirect` to an HTTP listener on the same hostname and a different port.\n3. rclone follows the redirect while preserving the WebDAV method.\n4. The plaintext listener receives both the Basic `Authorization` value and Cookie.\n\n## 5. Impact Assessment\n\nAn 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.\n\n## 6. Remediation Guidance\n\n- Reject every HTTPS-to-HTTP redirect before replay.\n- Forward authenticated requests by default only when scheme, hostname, and effective port are unchanged.\n- Strip authorization, cookies, proxy credentials, and configured secret headers on all other redirects.\n- Put necessary provider exceptions behind exact destination allowlists.\n- Cover `301`, `302`, `303`, `307`, and `308` in regression tests.","published":"2026-08-25T15:16:09.110Z","modified":"2026-10-28T02:31:09.768849885Z","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"Go","name":"github.com/rclone/rclone","fixedVersion":"1.75.0"}],"fix":{"url":"https://github.com/rclone/rclone/commit/59b513b0e74fd2943ccbb8891d5ce00f860e6d26","label":"rclone/rclone@59b513b"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/79xxx/CVE-2026-79779.json"},{"type":"ADVISORY","url":"https://github.com/rclone/rclone/security/advisories/GHSA-h4mf-4v27-hggj"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-79779"},{"type":"ADVISORY","url":"https://www.vulncheck.com/advisories/rclone-before-webdav-credential-exposure-via-https-to-http-redirect"},{"type":"WEB","url":"https://github.com/rclone/rclone/commit/59b513b0e74fd2943ccbb8891d5ce00f860e6d26"},{"type":"PACKAGE","url":"https://github.com/rclone/rclone"},{"type":"WEB","url":"https://github.com/rclone/rclone/releases/tag/v1.75.0"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-28T02:31:09.768849885Z"}}