# CVE-2026-79778: rclone WebDAV TUS nil-response denial of service

Source: https://junglewise.ai/threats/cve-2026-79778-rclone-webdav-tus-nil-response-denial-of-service  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-08-25. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-79778 · Severity: medium · CVSS 5.3 · Published 2026-08-25

rclone is a widely-used file synchronization and cloud storage tool that supports uploading files to WebDAV endpoints using the TUS protocol. A flaw in the TUS creation handler causes rclone to crash when a WebDAV endpoint resets connections during upload initialization. An attacker controlling or compromising the configured WebDAV endpoint can repeatedly trigger this crash, disrupting long-lived processes like VFS mounts or multi-remote CLI operations where the upload runs in unrecovered threads.

Technologies: [github.com/rclone/rclone (Go)](https://junglewise.ai/threats/technologies/github-com-rclone-rclone), [Rclone](https://junglewise.ai/threats/technologies/rclone). Vendors: [Go](https://junglewise.ai/threats/vendors/go), [Rclone](https://junglewise.ai/threats/vendors/rclone).

## Quick answers

**Is CVE-2026-79778 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-79778 being exploited in the wild.

**How severe is CVE-2026-79778?** Medium severity, with a CVSS score of 5.3, published 25 August 2026.

**Which products and versions are affected?** github.com/rclone/rclone (Go) SEMVER:introduced=0,fixed=1.75.0; Rclone before v1.75.0.

**Is there a fix for CVE-2026-79778?** Yes. github.com/rclone/rclone (Go): upgrade to 1.75.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-79778 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-79778?** Check whether you run github.com/rclone/rclone (Go) or Rclone at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- github.com/rclone/rclone (Go): upgrade to 1.75.0 or later

  ```sh
  go get github.com/rclone/rclone@v1.75.0
  ```


## Technical details

The vulnerability is a null-pointer dereference in the getTusLocationOrRetry function (backend/webdav/tus.go:45-59) that checks response.StatusCode before validating that the HTTP response is non-nil. When a transport error occurs during TUS creation POST (connection reset, timeout, DNS failure, TLS error, or proxy failure), the HTTP client returns (nil response, non-nil error). The code dereferences the nil response and panics. In VFS write paths (vfs/write.go:71-81), the panic occurs in an unrecovered goroutine and terminates the entire rclone process; RC jobs recover the panic and return an error instead. Attack preconditions: the attacker must control or compromise the configured WebDAV endpoint and initiate a TUS upload (e.g., by invoking Object.CreateUploader). The fix was released in v1.75.0 by checking resp == nil before accessing response fields and passing transport errors through the retry policy.

## Affected products

- rclone rclone before v1.75.0

## Identifiers

- CVE-2026-79778
- GHSA-3x6r-wxxg-53vv
- GO-2026-6183

## Timeline

- 2026-07-31: disclosed: GitHub Security Advisory GHSA-3x6r-wxxg-53vv published
- 2026-08: patched: Fix released in v1.75.0
- 2026-08-25: advisory

## References

- [https://github.com/rclone/rclone/security/advisories/GHSA-3x6r-wxxg-53vv](https://github.com/rclone/rclone/security/advisories/GHSA-3x6r-wxxg-53vv)
- [https://www.vulncheck.com/advisories/rclone-before-denial-of-service-via-tus-nil-response-panic](https://www.vulncheck.com/advisories/rclone-before-denial-of-service-via-tus-nil-response-panic)

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