# CVE-2026-93353 — 9001 copyparty

> As of 2026-09-28, CVE-2026-93353 is a MEDIUM-severity vulnerability in 9001 copyparty, CVSS v3.1 5.3, EPSS 0.3% (22.8th percentile). No Threadlinqs-tracked threat campaign has been attributed to CVE-2026-93353 as of 2026-09-28; the identifier is re-checked against the Threadlinqs threat corpus on every daily ingest.

**Last updated:** 2026-09-28

## What is CVE-2026-93353?

copyparty contains a volume restriction bypass vulnerability in its SFTP front end that allows authenticated SFTP users to create, remove, and truncate arbitrary paths outside permitted volume boundaries by exploiting three handlers that bypass the xvol volflag enforcement. The _mkdir, _rmdir, and _chattr handlers construct destination paths using vfs.get(), vn.canonical(), and os.path.join() without invoking the chk_ap access check, enabling attackers to traverse symlinks leaving a volume's top directory and perform unauthorized file creation, deletion, or truncation via SSH_FXP_SETSTAT operations on paths outside any volume the account is authorized to access.

The record classifies CVE-2026-93353 under weakness classes [CWE-59](https://intel.threadlinqs.com/cwe/CWE-59), [CWE-424](https://cwe.mitre.org/data/definitions/424.html). Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs low-privilege credentials, needs no user interaction, and has high impact on integrity. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 11 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 5.3 — MEDIUM (`CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N`)
- **CVSS v4.0 base score:** 6 (`CVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N`)
- **EPSS (FIRST):** 0.3% probability of exploitation in the next 30 days, higher than 22.8% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 3.6/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-09-24, last modified 2026-09-28

## Is CVE-2026-93353 being exploited?

It currently carries a trending score of 34 in the Threadlinqs vulnerability feed.

## Affected products and versions

- **9001**: copyparty

## How to fix CVE-2026-93353

No vendor patch reference has been recorded for CVE-2026-93353 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

## Threat activity tracking CVE-2026-93353

No threat campaign in the Threadlinqs corpus currently references CVE-2026-93353, in its CVE list or as an indicator. The linkage is recomputed from the live corpus on every daily ingest, so this section fills in as soon as a tracked campaign cites the identifier.

## Sources

Enriched from CVE.org, FIRST EPSS, NVD. Last verified by Threadlinqs on 2026-09-30. This product uses the NVD API but is not endorsed or certified by the NVD.

**Exploit and proof of concept**

- [euriconicacio.github.io — technical description](https://euriconicacio.github.io/blog/cve-2026-93353-a-volume-guard-enforced-one-call-site-at-a-time/)

**Third-party advisory**

- [vulncheck.com — third party advisory](https://www.vulncheck.com/advisories/copyparty-sftp-volume-restriction-bypass-via-mkdir-rmdir-chattr-handlers)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-93353
Full detection coverage and IOCs for threats exploiting CVE-2026-93353 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp