How severe is CVE-2020-26299?

CVE-2020-26299 has a CVSS score of 9.6/10, rated CRITICAL. Immediate patching is strongly recommended.

Which packages are affected by CVE-2020-26299?

CVE-2020-26299 affects the following packages: ftp-srv (npm). Ecosystems affected: npm.

How do I fix CVE-2020-26299?

Update ftp-srv to 4.4.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-26299 is resolved across your whole dependency graph.

How do I detect CVE-2020-26299 in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for ftp-srv, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2020-26299 if there is no patch (or I can't update yet)?

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.

Is CVE-2020-26299 actively exploited in the wild?

No public exploit code has been indexed for CVE-2020-26299 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2020-26299?

CVE-2020-26299 has an EPSS (Exploit Prediction Scoring System) score of 1.9%, placing it in the 79th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2020-26299?

CVE-2020-26299 is classified as Path Traversal (CWE-22). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2020-26299 published, and has it been updated?

CVE-2020-26299 was published on February 10, 2021 and was last updated on August 27, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦

📦 npm

Not in CISA KEV

CRITICAL severity

CVE-2020-26299 — ftp-srv

CRITICALFix: autovance/ftp-srv@457b859

CVE-2020-26299 is a critical-severity (CVSS 9.6) Path Traversal vulnerability in ftp-srv. A fix is available for ftp-srv — see the affected versions and patch details below.

File System Bounds Escape

Also known asGHSA-pmw4-jgxx-pcq9

Published

Feb 10, 2021

Updated

Aug 27, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

1.9%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs79th percentile — riskier than 79% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2020-26299 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,738 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

29other npm packages depend on this — each one inherits the vulnerability until it's patched upstream

ftp-srvnpm

22Kdownloads / week

Description

Impact

Clients of FTP servers utilizing ftp-srv hosted on Windows machines can escape the FTP user's defined root folder using the expected FTP commands, for example, CWD and UPDR.

Background

When windows separators exist within the path (\), path.resolve leaves the upper pointers intact and allows the user to move beyond the root folder defined for that user. We did not take that into account when creating the path resolve function.

Screen Shot 2020-12-15 at 6 42 52 PM

Patches

None at the moment.

Workarounds

There are no workarounds for windows servers. Hosting the server on a different OS mitigates the issue.

References

Issues: https://github.com/autovance/ftp-srv/issues/167 https://github.com/autovance/ftp-srv/issues/225

For more information

If you have any questions or comments about this advisory: Open an issue at https://github.com/autovance/ftp-srv. Please email us directly; [email protected].

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`ftp-srv`	all versions	4.4.0`npm install ftp-srv@4.4.0`

Affected Products

1 product · 1 configurations

Application

ftp-srvftp-srv_project

< 4.4.0

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for ftp-srv, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update ftp-srv to 4.4.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-26299 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.

Frequently Asked Questions

### Impact Clients of FTP servers utilizing `ftp-srv` hosted on Windows machines can escape the FTP user's defined root folder using the expected FTP commands, for example, `CWD` and `UPDR`. ### Background When windows separators exist within the path (`\`), `path.resolve` leaves the upper pointers intact and allows the user to move beyond the root folder defined for that user. We did not take that into account when creating the path resolve function. ![Screen Shot 2020-12-15 at 6 42 52 PM](https://user-images.githubusercontent.com/3375444/102293941-5a75fb80-3f05-11eb-9d71-0c190a8dcc75.pn