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CVE Record

CVE-2021-31800: Multiple path traversal vulnerabilities exist in smbserver.py in Impacket through 0.9.22.

Multiple path traversal vulnerabilities exist in smbserver.py in Impacket through 0.9.22. An attacker that connects to a running smbserver instance can list and write to arbitrary files via ../ directory traversal. This could potentially be abused to achieve arbitrary code execution by replacing /etc/shadow or an SSH authorized key.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

CVE-2021-31800 is a path traversal flaw in Impacket's smbserver.py through 0.9.22. If an organization runs that SMB server and an attacker can connect, the attacker may access or overwrite files outside the intended share, creating serious compromise risk.

Executive priority

Treat this as high priority where Impacket smbserver is used in labs, operations, or security tooling and reachable by others. It is lower urgency for systems with no running smbserver exposure, but version cleanup is still appropriate.

Technical view

Multiple directory traversal issues in smbserver.py allow connected attackers to use ../ paths to list and write arbitrary files. The CVE notes possible arbitrary code execution through replacement of sensitive files such as authentication material. Sources identify upstream fix activity and Fedora package advisories.

Likely exposure

Exposure is limited to environments running an Impacket smbserver instance through 0.9.22, especially where that service is reachable by untrusted users or networks. Installed Impacket libraries alone are not enough evidence of exposure without smbserver use.

Exploitation context

The source bundle does not show CISA KEV listing or cited evidence of active exploitation. Exploitation requires connection to a running smbserver instance and abuses path traversal to escape intended file boundaries.

Researcher notes

The affected product metadata in the CVE bundle is sparse, but the description clearly names Impacket smbserver.py through 0.9.22. The bundle includes upstream code references, a fixing commit, releases page, and Fedora advisories, but no CVSS vector or KEV evidence.

Mitigation direction

  • Upgrade Impacket beyond 0.9.22 or use vendor-patched packages.
  • Apply relevant Fedora advisories where Fedora packages are used.
  • Disable Impacket smbserver instances that are not operationally required.
  • Restrict SMB server reachability to trusted hosts only.
  • Run temporary SMB services with least privilege and isolated directories.

Validation and detection

  • Inventory systems with Impacket installed and record package versions.
  • Identify hosts actively running Impacket smbserver.py or related SMB server tooling.
  • Confirm no exposed smbserver instance runs Impacket through 0.9.22.
  • Review SMB service logs for unexpected connections or file write activity.
  • Check sensitive file integrity on hosts that ran exposed smbserver instances.
Prepared
Confidence
medium
Sources
7

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

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ATT&CK lookup starting points

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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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description · low confidence lookup

File access behavior lookup

The CVE wording references file access or upload behavior, so file telemetry and web shell review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

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CVE-2021-31800 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
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.

0CVSS vectors
0Timeline events
0ADP providers
7Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/an/an/aListed
Weakness

CWE details

No CWE listed

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