NVD / CVE Program· CNA GitHub_M

CVE-2026-88017: rclone: FTP cross-session auth-proxy backend confusion

Noroxi assessment

Priority: Monitor (action score 29/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 0.23% (FIRST EPSS).
Anyone who can reach it over the internet can trigger it. A low-privileged account is enough. A user must open a link or visit a page. No special conditions are required; it is repeatable.
Fixed version: rclone rclone 1.75.1.

Low priority for now. Upgrade to rclone rclone 1.75.1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

rclone is a command-line program to sync files and directories to and from different cloud storage providers. From 1.64.0 until 1.75.1, the FTP auth-proxy driver in cmd/serve/ftp/ftp.go stores one obscured password per username in the server-wide userPass map[string]string instead of binding the credential or VFS to the authenticated session. If two accepted credentials use the same username but resolve to different proxy backends, a later CheckPasswd login overwrites userPass[user], and subsequent getVFS operations on the first session are reauthorized with the later password. The first session can then read, create, overwrite, rename, or delete objects using the second credential’s backend authority. Exploitation requires the later same-username login to occur while the first session remains open. This issue is fixed in version 1.75.1.

HighCVSS 7.3 · v3.1—No exploit Fix available

Published: Sep 10, 2026
Updated: Sep 14, 2026
EPSS: 0.2% · 14th percentile
CWE: CWE-488

Report tools

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Action score

Monitor

Low priority for now.

CVSS: 29 / 40 · 7.3 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.2%

CISA SSVC decision

Exploitation: none
Automatable: no
Technical impact: total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD: —
CNA · GitHub_M: 7.3; NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

Not in KEV: no record of exploitation in the wild
No public exploit code on record
A fix has been released

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

Vendor	Product	CPE
rclone	rclone	cpe:2.3:a:rclone:rclone

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

rclone rclone1.64.0 and later · before 1.75.1

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

rclone rclone
- >= 1.64.0, < 1.75.1affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Ecosystem	Package	Affected range	Fix
Debian:12	rclone	from 0	—
Go	github.com/rclone/rclone	from 1.64.0 · before 1.75.1	1.75.1

Same product

rclone: all records

Other highest-scoring records for the same primary product.

CVE-2026-41176Rclone: Unauthenticated options/set allows runtime auth bypass, leading to sensitive operations and command execution
46Plan
CVE-2026-88018rclone serve s3: --auth-proxy without --auth-key authenticates nobody - full SigV4 signature bypass
39Monitor
CVE-2026-49980Rclone: Unauthenticated command execution in `rclone rcd --rc-serve` via inline remote instantiation, bypassing CVE-2026-41179 fix
39Monitor

Published before and after this one in the same product

← EarlierCVE-2026-88015Sep 10, 2026 · rclone local: crafted Range request against a translated symlink panics (DoS)
21Monitor
← EarlierCVE-2026-88016Sep 10, 2026 · rclone: Directory metadata (chmod/chown/chtimes) applied through a planted symlink in rclone local --links escapes the destination
28Monitor
Later →CVE-2026-88044Sep 10, 2026 · rclone: RC per-server auth-proxy bypass
36Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / package	Fixed version	Source
rclone rclone	1.75.1 · description	Vendor (CNA)
Go:github.com/rclone/rclone	1.75.1	Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

rclone/rclonecommit c6af0b5

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

Anyone who can reach it over the internet can trigger it.
A low-privileged account is enough.
A user must open a link or visit a page.
No special conditions are required; it is repeatable.

If successful

Confidentiality: high · data can be read
Integrity: high · data or configuration can be modified
Availability: none

Attack vector: Network
Attack complexity: Low
Privileges required: Low
User interaction: Required
Scope: Unchanged
Confidentiality impact: High
Integrity impact: High
Availability impact: None

Weakness class (CWE)

CWE-488 · Exposure of Data Element to Wrong Session

CVSS vector

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

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Attack patterns (CAPEC)

ATT&CK techniques

Change log

Fix✗ → ✓Sep 28, 2026, 10:47 PM UTC

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References

github.com/rclone/rclone/commit/c6af0b57c2b4af848bc968c2b407354476184b99

Show all references (2 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

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