Security readout for executives and security teams
Plain-English summary
PCMan FTP Server 2.0.7 can be remotely crashed through handling of the FTP USER command. The impact is service disruption, not data theft or takeover based on the provided sources. Public exploit references exist, but the bundle does not show confirmed active exploitation or a named patch.
Executive priority
Treat this as a moderate availability risk. Prioritize remediation if the FTP service is internet-facing, business-critical, or lacks operational monitoring. It is less urgent than code execution or data exposure flaws, but public exploit availability raises operational risk.
Technical view
CVE-2021-4432 affects the USER command handler in PCMan FTP Server 2.0.7. It is a remote, unauthenticated denial-of-service issue scored CVSS 3.1 5.3 with low availability impact and mapped to CWE-404. The affected code area is not further specified in the sources.
Likely exposure
Exposure is most relevant where PCMan FTP Server 2.0.7 is running and reachable over a network, especially internet-facing FTP services. Environments without this product/version, or with FTP access tightly restricted, are unlikely to be affected.
Exploitation context
The sources state the exploit has been publicly disclosed and may be used. The CVE is not listed as KEV in the provided bundle, and no cited source confirms active exploitation in the wild.
Researcher notes
The record identifies the component and outcome but not root-cause detail, patch status, or vendor remediation. Avoid assuming impact beyond denial of service. Public exploit references support disclosure, not confirmed active exploitation.
Mitigation direction
- Identify and remove any unnecessary PCMan FTP Server instances.
- Restrict FTP access to trusted networks or VPN paths only.
- Check vendor or maintainer guidance for updates or replacement options.
- Add monitoring for FTP crashes, restarts, and abnormal login attempts.
- Use firewall rules to limit exposure until remediation is confirmed.
Validation and detection
- Inventory hosts for PCMan FTP Server 2.0.7.
- Confirm whether FTP is reachable from the internet or untrusted networks.
- Review service logs for repeated USER command failures or restarts.
- Verify compensating controls restrict unauthenticated remote access.
- Track vendor advisories because no patch is named in the sources.
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
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-404: 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.
Open ATT&CK lookupCVE-2021-4432 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Medium
- CVSS
- 5.3 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
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.
CVSS vector scores
1 official scoreWe 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.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L3.91.4Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
5.3MediumVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Source materials
- CVE List V5 sourceCVE List V5
- https://vuldb.com/?id.250719CVE reference · vdb-entry
- https://vuldb.com/?ctiid.250719CVE reference · signature, permissions-required
- https://packetstormsecurity.com/files/163104/PCMan-FTP-Server-2.0.7-Denial-Of-Service.htmlCVE reference · related
- https://0day.today/exploit/description/36412CVE reference · exploit
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Resource Shutdown or Release
Improper Resource Shutdown or Release represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.