CyberSecBulletin
CVE-2026-87886Exploited in the wildNVD status: Analyzed

Acronis Backup Incorrect Default Permissions

Published Updated By the CyberSecBulletin desk

CVE-2026-87886 is a high-severity incorrect default permissions vulnerability in Acronis Backup plugin for cPanel & WHM from Acronis, with a CVSS 3.0 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists version 1.9.3.1021 as the first without the flaw, so updating Acronis Backup plugin for cPanel & WHM to that release or later removes the exposure. CISA added it to the Known Exploited Vulnerabilities catalogue on September 16, 2026, which means attacks have been observed in the wild.

Patch now

Attackers are already exploiting this vulnerability, according to CISA.

What to do

  1. Update Acronis Backup plugin for cPanel & WHM to 1.9.3.1021 or a later version.
  2. Update Acronis Backup extension for Plesk to 1.8.11.638 or a later version.
  3. Update Acronis Backup plugin for DirectAdmin to 1.2.3.238 or a later version.
  4. CISA's required action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
  5. Read the advisory on security-advisory.acronis.com for workarounds and exact fixed builds.

Affected products and versions

VendorProductAffected versionsFixed in
AcronisAcronis Backup plugin for cPanel & WHMbefore 1.9.3.10211.9.3.1021
AcronisAcronis Backup extension for Pleskbefore 1.8.11.6381.8.11.638
AcronisAcronis Backup plugin for DirectAdminbefore 1.2.3.2381.2.3.238
AcronisAcronis Backupbefore 1.2.3; before 1.8.11; before 1.9.3; 1.9.31.2.3, 1.8.11, 1.9.3

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by CNA (acronis.com).

Official description

Local privilege escalation due to insecure file permissions. The following products are affected: Acronis Backup plugin for cPanel & WHM (Linux) before build 1.9.3.1021, Acronis Backup extension for Plesk (Linux) before build 1.8.11.638, Acronis Backup plugin for DirectAdmin (Linux) before build 1.2.3.238.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Incorrect Default Permissions

During installation, installed file permissions are set to allow anyone to modify those files.

How developers prevent this class of flaw

  • The architecture needs to access and modification attributes for files to only those users who actually require those actions.
  • Compartmentalize the system to have safe areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area. Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.

More Incorrect Default Permissions vulnerabilities (CWE-276)

Timeline

  1. Added to CISA's Known Exploited Vulnerabilities catalogue.
  2. CVE record published.
  3. CISA published its SSVC assessment (exploitation: active, automatable: no, technical impact: total).
  4. Record last changed materially (score, affected products, status or references).
  5. Deadline for US federal agencies to remediate, set by CISA.

References

Third-party and government advisories

Our coverage

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