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CVE Record

CVE-2026-39983: FTP Command Injection via CRLF in basic-ftp

basic-ftp is an FTP client for Node.js. Prior to 5.2.1, basic-ftp allows FTP command injection via CRLF sequences (\r\n) in file path parameters passed to high-level path APIs such as cd(), remove(), rename(), uploadFrom(), downloadTo(), list(), and removeDir(). The library's protectWhitespace() helper only handles leading spaces and returns other paths unchanged, while FtpContext.send() writes the resulting command string directly to the control socket with \r\n appended. This lets attacker-controlled path strings split one intended FTP command into multiple commands. This vulnerability is fixed in 5.2.1.

HighCVSS 8.6Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

CVE-2026-39983 affects the Node.js FTP client library basic-ftp before 5.2.1. Applications that pass untrusted file paths into its high-level FTP APIs could let an attacker inject extra FTP commands, potentially changing or deleting remote files.

Executive priority

Treat as high priority for systems that move business files over FTP, especially internet-facing upload or partner-transfer workflows. Upgrade promptly, then validate whether untrusted path data can reach affected APIs.

Technical view

basic-ftp did not neutralize CRLF control characters in path parameters for APIs including cd(), remove(), rename(), uploadFrom(), downloadTo(), list(), and removeDir(). FtpContext.send() then wrote the command to the FTP control socket, allowing one intended command to be split into multiple FTP commands. Version 5.2.1 fixes this.

Likely exposure

Exposure is most likely in Node.js services, automation jobs, file-transfer portals, or integrations that use basic-ftp below 5.2.1 and accept filenames, directory names, or remote paths from users, partners, queues, APIs, or imported data.

Exploitation context

The bundle marks KEV as false and provides no evidence of active exploitation. The flaw is still serious because it is network-reachable in affected application flows, requires low complexity, and can impact integrity on the FTP server.

Researcher notes

The key primitive is FTP command injection through CRLF in path parameters, mapped to CWE-93. The provided evidence names the affected library, vulnerable API surface, root cause, fixed version, commit, release, and Red Hat tracking, but not real-world exploitation.

Mitigation direction

  • Upgrade basic-ftp to version 5.2.1 or later.
  • Review applications for untrusted input passed to basic-ftp path APIs.
  • Block or reject control characters in FTP path inputs at application boundaries.
  • Check Red Hat advisories if using affected Red Hat-distributed packages.
  • Follow vendor guidance for any downstream package-specific remediation.

Validation and detection

  • Inventory package-lock, yarn.lock, pnpm-lock, and SBOM entries for basic-ftp versions.
  • Confirm deployed runtime artifacts use basic-ftp 5.2.1 or later.
  • Trace user-controlled path inputs into basic-ftp high-level APIs.
  • Review FTP logs for unexpected command patterns around user-supplied path operations.
  • Verify dependency scanners identify CVE-2026-39983 after rescanning.
Prepared
Confidence
medium
Sources
10

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · low confidence lookup

CWE-93: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

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description · low confidence lookup

Execution behavior lookup

The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

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cve · low confidence lookup

CVE-2026-39983 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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Vulnerability profileCVE Program record
Severity
High
CVSS
8.6 (3.1)
Known Exploited
No
Published

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

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

2CVSS vectors
5Timeline events
2ADP providers
9Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: pocAutomatable: yesTechnical Impact: partial

CVSS vector scores

2 official scores

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
8.6CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:L3.94.7GitHub_M
8.6CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:L3.94.7redhat-SADP

Vulnerability scoring details

Base CVSS 3.1 score

8.6High
CVSS 3.1 vector shape for CVE-2026-39983Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. ADP timelineredhat-SADP

    Made public.

  3. CVE publishedCVE Program

    The CVE record was published.

  4. ADP timelineredhat-SADP

    Reported to Red Hat.

  5. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
redhat-SADPbasic-ftp: basic-ftp: Command injection via CRLF sequences in file path parameters
other:Red Hat severity ratingcvssV3_1
  • 2026-04-09T18:02:16.209Z: Reported to Red Hat.
  • 2026-04-09T17:05:46.228Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
patrickjuchlibasic-ftp< 5.2.1Listed
Weakness

CWE details

CWE-93

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-93 · source CWE mapping

Improper Neutralization of CRLF Sequences ('CRLF Injection')

Improper Neutralization of CRLF Sequences ('CRLF Injection') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs