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Vulnerability record · CVE-2021-31800 · published 5 May 2021

CVE-2021-31800: Secureauth impacket path traversal vulnerability

Secureauth · Impacket

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.

9.8 CVSS 3.1 Critical EPSS 19% · top 2.7% CWE-22 · Path traversal
9.8CVSS 3.1 base score, v2 7.5
19%EPSS exploitation probability, 30 days
NoNot in CISA KEV
2Affected product versions listed by NVD
18References
17 Jun 2026Last modified by NVD

Description

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.

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

Affected products

2 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/SecureAuthCorp/impacket/blob/cb6d43a677c338db930bc4e9161620832c1ec624/impacket/smbserver.py#L2008 Third Party Advisory
https://github.com/SecureAuthCorp/impacket/blob/cb6d43a677c338db930bc4e9161620832c1ec624/impacket/smbserver.py#L2958 Third Party Advisory
https://github.com/SecureAuthCorp/impacket/blob/cb6d43a677c338db930bc4e9161620832c1ec624/impacket/smbserver.py#L3485 Third Party Advisory
https://github.com/SecureAuthCorp/impacket/blob/cb6d43a677c338db930bc4e9161620832c1ec624/impacket/smbserver.py#L876 Third Party Advisory
https://github.com/SecureAuthCorp/impacket/commit/49c643bf66620646884ed141c94e5fdd85bcdd2f PatchThird Party Advisory
https://github.com/SecureAuthCorp/impacket/releases Release NotesThird Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IPXDPWCAPVX3UWYZ3N2T5OL
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/KRV2C5DATXBHG6TF6CEEX54
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UF56LYB27LHEIFJTFHU3M75
https://github.com/SecureAuthCorp/impacket/blob/cb6d43a677c338db930bc4e9161620832c1ec624/impacket/smbserver.py#L2008 Third Party Advisory
https://github.com/SecureAuthCorp/impacket/blob/cb6d43a677c338db930bc4e9161620832c1ec624/impacket/smbserver.py#L2958 Third Party Advisory
https://github.com/SecureAuthCorp/impacket/blob/cb6d43a677c338db930bc4e9161620832c1ec624/impacket/smbserver.py#L3485 Third Party Advisory
https://github.com/SecureAuthCorp/impacket/blob/cb6d43a677c338db930bc4e9161620832c1ec624/impacket/smbserver.py#L876 Third Party Advisory
https://github.com/SecureAuthCorp/impacket/commit/49c643bf66620646884ed141c94e5fdd85bcdd2f PatchThird Party Advisory
https://github.com/SecureAuthCorp/impacket/releases Release NotesThird Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IPXDPWCAPVX3UWYZ3N2T5OL
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/KRV2C5DATXBHG6TF6CEEX54
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UF56LYB27LHEIFJTFHU3M75

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Source: NIST National Vulnerability Database (record CVE-2021-31800), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.