Acronis Backup Incorrect Default Permissions Vulnerability
Acronis · Backup
Acronis Backup contains an incorrect default permissions flaw in its Linux plugins and extensions for cPanel & WHM (before build 1.9.3.1021), Plesk (before build 1.8.11.638), and DirectAdmin (before build 1.2.3.238). An attacker with a local, low-privileged account on the affected system can exploit the insecure file permissions to escalate privileges, with no user interaction required.
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.
- Exploited
- Yes, in CISA KEV
- Reports
- 0
- Tactics
- 4/15
How an attack unfolds
Based on MITRE ATT&CKA public catalogue of the techniques attackers use, maintained by MITRE. Patchfirst uses it to describe what attackers do with a vulnerability. mappings. Select a step to see the evidence.How attackers get in
What they do
Exploitation timelineDated milestones for a CVE: when it was disclosed, when exploit code became public, when exploitation was confirmed, and when threat reports named it.
First seen exploited 2 days before it was disclosed.
- First seen exploitedVulnCheck KEV evidence2 days before
- Added to CISA KEVEU database agrees1 day before
- Disclosedday 0
CISA KEV listing is when exploitation was confirmed, not necessarily the first attack.
MITRE ATT&CKA public catalogue of the techniques attackers use, maintained by MITRE. Patchfirst uses it to describe what attackers do with a vulnerability. techniques
2 TechniqueOne specific attacker behaviour in MITRE ATT&CK, such as T1190 “Exploit Public-Facing Application”. IDs with a dot, like T1059.004, are sub-techniques., grouped by TacticThe attacker’s goal at a stage of an attack in MITRE ATT&CK, such as Initial Access or Persistence. Each technique belongs to one or more tactics. in kill-chain order, 2 cited passages 2Initial AccessTA0001
Local low-privilege account already present; no remote exploit
Local privilege escalation due to insecure file permissions
Privilege EscalationTA0004
Insecure permissions enable escalation to root
Local privilege escalation due to insecure file permissions
Detection
0 rules for this CVE · 87 general rules for its techniquesRules for this CVE
0Sigma ruleAn open, vendor-neutral detection rule for log data. Security teams convert Sigma rules into searches for their own SIEM. that reference CVE-2026-87886 directly.CVE-specific rules are not available in this build. Search SigmaHQ ↗
General rules for this CVE’s techniques
These detect the technique in general, not this specific vulnerability.
Valid AccountsT107856 general rules
- Win Susp Computer Name Containing Samtheadmincriticaltest
- Account Created And Deleted Within A Close Time Framehightest
- Activity From Anonymous IP Addresshightest
- Atypical Travelhightest
- Azure AD Threat Intelligencehightest
- Azure Subscription Permission Elevation Via AuditLogshightest
- External Remote SMB Logon from Public IPhightest
- Impossible Travelhightest
Exploitation for Privilege EscalationT106831 general rules
- Exploiting CVE-2019-1388criticalstable
- Audit CVE Eventcriticaltest
- HackTool - SysmonEOP Executioncriticaltest
- InstallerFileTakeOver LPE CVE-2021-41379 File Create Eventcriticaltest
- Possible Coin Miner CPU Priority Paramcriticaltest
- Potential CVE-2021-41379 Exploitation Attemptcriticaltest
- Potential SystemNightmare Exploitation Attemptcriticaltest
- Sudo Privilege Escalation CVE-2019-14287 - Builtincriticaltest
Sigma rules © SigmaHQ, Detection Rule License 1.1; linked, not reproduced.
What security researchers reported
Not named in any threat report yetAlso mentioned in 34 community threat pulses (AlienVault OTX)
Weaker evidencePulses are indicator collections that anyone can publish. A mention is not confirmation of exploitation.
- Actively_Exploited_Kev | Oct 31, 202630 Oct 2026
- Actively_Exploited_Kev | Oct 30, 202629 Oct 2026
- Actively_Exploited_Kev | Oct 29, 202628 Oct 2026
- Actively_Exploited_Kev | Oct 28, 202627 Oct 2026
- Actively_Exploited_Kev | Oct 27, 202626 Oct 2026
- Actively_Exploited_Kev | Oct 24, 202623 Oct 2026
- 28 more on OTX