CVE-2026-87886: Acronis Backup Incorrect Default Permissions Vulnerability

Should you act?

Exploited: patch now if you run it

CISA has confirmed exploitation in the wild. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• Yes, if you run Acronis Backup. CISA added this CVE to its Known Exploited Vulnerabilities catalog on 2026-09-16, which means there is reliable evidence of exploitation in the wild. US federal agencies must remediate by 2026-09-19; treat that as the outer limit, not the target.
• EPSS 0.2%, percentile 13: FIRST’s model estimates a 0.2% chance of exploitation activity in the next 30 days, higher than 13% of all scored CVEs (low). EPSS is a probability, not a verdict.
• Needs local access needed. Lower urgency for most teams unless an attacker could already run code on the machine.
• Editorial verdict: Check exposure. Acronis Backup cPanel Plugin CVE-2026-87886: Exploited LPE — Only hosting servers running the Acronis Backup plugin for cPanel & WHM, Plesk or DirectAdmin are affected; on those, especially multi-tenant cPanel boxes, update the plugin now because it is being exploited.

What it is

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.

CISA’s summary

Acronis Backup plugin for cPanel & WHM and extension for Plesk contains an incorrect default permissions vulnerability that could allow for privilege escalation.

Weakness type: CWE-276.

Product: Acronis Backup · Assigned by: Acronis · Published: 2026-09-17

Affected and fixed versions

Severity scores

• Attack vector: local access needed
• Attack complexity: low
• Privileges required: low (any account)
• User interaction: none
• Scope: unchanged

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: added 2026-09-16; federal due date 2026-09-19. Known ransomware use: Unknown.
• CISA 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.
• CISA SSVC assessment: exploitation active, automatable no, technical impact total.
• FIRST EPSS (model of 2026-10-21): 0.23% probability of exploitation activity in the next 30 days; percentile 13.

Timeline

• 2026-09-15 — erroneo.us brief: Acronis Backup cPanel Plugin CVE-2026-87886: Exploited LPE
• 2026-09-16 — Added to CISA’s Known Exploited Vulnerabilities catalog
• 2026-09-17 — CVE record published by Acronis
• 2026-09-18 — CVE record last updated
• 2026-09-19 — CISA remediation deadline for US federal agencies

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vendor and project advisories, patches

1. SEC-10986 security-advisory.acronis.com

Vulnerability records

1. CVE.org record CVE-2026-87886 cve.org
2. NVD entry CVE-2026-87886 nvd.nist.gov

Government

1. CISA Known Exploited Vulnerabilities catalog entry cisa.gov
2. Listed in CISA KEV notes (cisa.gov) cisa.gov
3. Listed in CISA KEV notes (cisa.gov) cisa.gov

All exploited Acronis vulnerabilities · Today’s Security Digest