CVE-2023-37474 is a high-severity (CVSS 7.5) Path Traversal vulnerability in copyparty. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for copyparty — see the affected versions and patch details below.
Path traversal in copyparty
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
Exploitation and automatability from CISA’s SSVC triage for CVE-2023-37474.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
copypartyReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
Summary
All versions before 1.8.2 have a path traversal vulnerability, allowing an attacker to download unintended files from the server.
Details
Unauthenticated users were able to retrieve any files which are accessible (according to OS-level permissions) from the copyparty process. Usually, this is all files that are readable by the OS account which is used to run copyparty.
The vulnerability did not make it possible to list the contents of folders, so an attacker needs to know the full absolute path to the file, or the relative path from where copyparty is installed.
Some methods of running copyparty (prisonparty, the nix package, and docker) had a mitigating effect, mostly reducing the attack scope to files inside copyparty volumes, and possibly the copyparty config file.
Checking for attacks
Please keep in mind that, if an attacker were to find a way to overwrite the logs, for example by discovering the password to another service with sufficient privileges, then the following approaches cannot be trusted.
if copyparty was only accessible through a reverse proxy, then all attacks would be visible in the webserver access-log as URLs which contain both .cpr/ and %2F
- nginx:
(gzip -dc access.log*.gz; cat access.log) | sed -r 's/" [0-9]+ .*//' | grep -E 'cpr/.*%2[^0]' | grep -vF data:image/svg
However, if copyparty was directly accessible from the internet, then any successful attacks (file retrievals) would unfortunately leave no trace. That said, it is very probable that an attacker would make at least one invalid attempt, which would become apparent in the copyparty server log, detectable with grep -aE '(Errno|Permission).*\.cpr/' revealing the following:
- python2 example:
[IOError] [Errno 13] Permission denied: '/etc/shadow', .cpr//etc/shadow - python3 example:
[PermissionError] [Errno 13] Permission denied: b'/etc/shadow', .cpr//etc/shadow
Providing an exact command for this approach is difficult, as it depends on how copyparty is deployed;
- if copyparty was running as a systemd service:
journalctl -am | grep -aE '(Errno|Permission).*\.cpr/' - if copyparty was logging to a compressed file:
xz -kdc thefilename.xz | grep -aE '(Errno|Permission).*\.cpr/' - if the copyparty log is available in a plaintext file:
grep -aE '(Errno|Permission).*\.cpr/' thefilename.txt
PoC / attack example
curl -sik http://127.0.0.1:3923/.cpr/%2Fetc%2Fpasswd
curl -sik http://127.0.0.1:3923/.cpr/..%2F..%2F..%2F..%2F..%2Fetc%2Fpasswd
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | copyparty | all versions | 1.8.2pip install --upgrade 'copyparty==1.8.2' |
Affected Products
copyparty9001Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for copyparty, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update copyparty to 1.8.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-37474 is resolved across your whole dependency graph.
Workarounds
Resolve every user-supplied path to its canonical form and reject anything that escapes the intended directory, and run the component under an account that has no read or write access outside the directory it legitimately serves.
How to detect CVE-2023-37474
A community-maintained Nuclei template exists for this CVE. You can scan for it directly:
nuclei -id cve-2023-37474 -u https://target- Template
- Copyparty <= 1.8.2 - Directory Traversal
- Severity
- high
- Impact
- Unauthenticated attackers can exploit path traversal in the .cpr subfolder to read arbitrary files from the file server, potentially accessing sensitive system files and user data stored outside the web document root.
- Remediation
- Update Copyparty to version 1.8.2 or later that properly validates file paths in the .cpr subfolder and prevents directory traversal attacks.
Template by ProjectDiscovery nuclei-templates (shankar acharya, theamanrawat), MIT licensed. View the full template. Scan only systems you are authorised to test.
Frequently Asked Questions
Is CVE-2023-37474 in your dependencies?
Find it across PyPI, including transitive dependencies.