CVE-2020-36254Network attack vector

Directory permission modification via unchecked SCP filename

Published Feb 25, 2021 · Updated Dec 3, 2025

Improper filename validation in Dropbear scp before 2020.79 allows remote attackers to change local target-directory permissions. The sink() routine accepts a server-supplied empty or dot filename in a directory control record and applies its mode to the current destination directory. The victim must initiate an SCP download from an attacker-controlled SSH server; the bounded consequence is modification of that directory's permissions.

CVSS severity8.1
High
EPSS probability1.80%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper filename validation in Dropbear scp before 2020.79 allows remote attackers to change local target-directory permissions. The sink() routine accepts a server-supplied empty or dot filename in a directory control record and applies its mode to the current destination directory. The victim must initiate an SCP download from an attacker-controlled SSH server; the bounded consequence is modification of that directory's permissions.

The record

CVE
CVE-2020-36254
Published
Feb 25, 2021
Updated
Dec 3, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
T1222.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 25, 2021CVE publishedPublication date reported by the CVE source.
  2. Dec 3, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

8.1CISA-ADPCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
6.8NVDAV:N/AC:M/Au:N/C:P/I:P/A:P
8.1NVDCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1222.002File and Directory Permissions Modification: Linux and Mac Permissions

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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