rclone before v1.75.0 Denial of Service via TUS nil-response panic

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

rclone before v1.75.0 contains a denial of service vulnerability in the WebDAV TUS creation handler that dereferences a nil response before checking for transport errors. A malicious or compromised configured endpoint can reset connections during TUS uploads to trigger a panic that terminates unrecovered goroutines and halts unrelated work in long-lived processes.

Source published

25 Aug 2026 15:16:08 UTC

Source modified

25 Aug 2026 16:12:58 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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CVSS 4.0 · 6.0 CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

CVSS 3.1 · 5.3 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:H

rclone before v1.75.0 contains a denial of service vulnerability in the WebDAV TUS creation handler that dereferences a nil response before checking for transport errors. A malicious or compromised configured endpoint can reset connections during TUS uploads to trigger a panic that terminates unrecovered goroutines and halts unrelated work in long-lived processes.

Source published

Aug 25, 2026, 3:16:08 PM (timezone not stated)

Source modified

Aug 25, 2026, 4:12:58 PM (timezone not stated)

Observed here

11 Nov 2026 16:09:55 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

EUVD CVSS 4.0 · 6.0 CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

rclone before v1.75.0 contains a denial of service vulnerability in the WebDAV TUS creation handler that dereferences a nil response before checking for transport errors. A malicious or compromised configured endpoint can reset connections during TUS uploads to trigger a panic that terminates unrecovered goroutines and halts unrelated work in long-lived processes.

Source published

25 Aug 2026 16:17:29 UTC

Source modified

10 Sep 2026 20:46:19 UTC

Observed here

25 Oct 2026 16:19:10 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 4.0 · [email protected] · Secondary · 6.0 CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CVSS 3.1 · [email protected] · Secondary · 5.3 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:H

## 1. Summary A transport failure during the initial Infinite Scale TUS creation POST can return `(nil response, non-nil error)`. Rclone dereferences the nil response before processing the error and panics. The production `CreateUploader` path reproduced the crash against a closed endpoint. The security case is deployment-dependent. A one-shot upload already fails when its endpoint resets, while RC jobs recover panics in `fs/rc/jobs/job.go` and return a job error. The incremental denial of service is strongest in a long-lived VFS mount or concurrent/multi-remote CLI process where the upload runs in an unrecovered goroutine and the panic terminates unrelated work. ## 2. Affected Assets & Attack Surface - Verified rclone revision: `a0c09f1381ae93e2a9a33c529d170186c61ad058` (`v1.74.0-240-ga0c09f138`) - Current-master check: `backend/webdav/tus.go` was unchanged at master commit `961266888fe797390c535386f3b3aa46f4853602` on 2026-07-18 - Response evaluation: `backend/webdav/tus.go:45-59` - Creation path: `backend/webdav/tus.go:61-107` - Unrecovered VFS caller: `vfs/write.go:71-81` - Contained RC caller: `fs/rc/jobs/job.go:107-115` - Configuration: Infinite Scale WebDAV uploads using TUS - Code triggers: any pre-response transport failure, including refusal, reset, timeout, DNS/TLS/proxy failure, or cancellation - Security trigger: a malicious/compromised configured endpoint resets an upload in a long-lived or multi-workload process ## 3. Technical Root Cause Analysis `getTusLocationOrRetry` switches on `resp.StatusCode` before checking whether `resp` is nil or handling the accompanying error. A nil response is valid when the HTTP transaction fails before a response is parsed. There is no recovery boundary in the WebDAV operation itself. Whether the panic is process-fatal depends on its caller: the VFS write path starts `operations.Rcat` in an unrecovered goroutine (`vfs/write.go:71-81`), whereas RC jobs wrap their function in `recover` (`fs/rc/jobs/job.go:107-115`). ## 4. Proof-of-Concept & Evidence 1. Configure the actual Infinite Scale creation path to a closed local endpoint. 2. Invoke `Object.CreateUploader`. 3. The POST returns a transport error and no response. 4. `getTusLocationOrRetry` dereferences `resp.StatusCode` and panics. A remote endpoint can produce the same `(nil response, non-nil error)` state by accepting and resetting the connection before returning an HTTP response. TLS prevents arbitrary response modification but does not prevent the configured endpoint from closing or resetting its own connection. Refusal, DNS, TLS, proxy, and cancellation failures exercise the code defect but do not by themselves identify a remote security actor. ## 5. Impact Assessment In an unrecovered CLI or VFS upload goroutine, the panic terminates the rclone process and any unrelated work it hosts. A hostile configured endpoint can repeat the condition whenever the victim initiates a TUS upload. RC jobs are excluded from the process-wide impact because their execution boundary recovers the panic and records an error. In a one-shot process dedicated to the hostile endpoint, the incremental security impact over an ordinary transport error is limited. ## 6. Remediation Guidance - Check `resp == nil` before accessing response fields. - Pass transport errors through the existing retry policy and return a normal error after exhaustion. - Test refusal, reset, timeout, DNS, TLS, proxy, and cancellation paths. - Add panic containment to long-lived worker goroutines as defense in depth; keep nil handling as the primary fix.

Source published

5 Aug 2026 20:26:07 UTC

Source modified

25 Sep 2026 14:25:57 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:H

Publisher rating · MODERATE

During WebDAV Infinite Scale TUS upload creation, a transport failure can return a nil HTTP response along with an error. When handling the failure, rclone dereferences the nil response before checking the error, causing a panic that can crash the process in unrecovered contexts such as VFS mounts.

Source published

18 Aug 2026 16:38:10 UTC

Source modified

25 Sep 2026 14:25:57 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

OSV · upstream source license applies

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · OSV · upstream source license applies. Source text is retained; field grouping and change labels are provided by ChangeIntel.