What is CVE-2026-87886?

CVE-2026-87886 is Acronis Backup Incorrect Default Permissions Vulnerability. The supplied enrichment data classifies it as Unclassified mapped to CWE-276 CWE-276.

Which versions are affected?

Affected product and version evidence is listed in the product table above. Current public advisories should be checked for exact version scope before patch targeting is finalized.

Is there active exploitation?

Yes: CISA KEV signal present. If exploitation is not confirmed from current sources, teams should document that status and continue monitoring KEV, vendor, and telemetry updates.

Is there a public exploit?

7 public PoC repositories reported; 1 marked weaponized in current dataset. Public exploit or PoC availability should raise triage priority, especially for exposed or business-critical systems.

How can defenders detect it?

Start with Not reported where available. Look for vulnerability-class behavior, product errors, suspicious authentication events, exploit probes, and abnormal process activity based only on evidence that applies to the affected product.

How should teams prioritize it?

Prioritize CVE-2026-87886 using CVSS 7.8, EPSS 0%, KEV status, public PoC status, and asset exposure. Internet-facing, privileged, or business-critical deployments should be handled first.

Are workarounds available?

The supplied mitigation guidance says to apply vendor patches and restrict external exposure until fixed. Fixed-version evidence is listed in the mitigation section above.

Which threat actors are linked publicly?

No public threat actor linkage is confirmed from current sources. Do not attribute exploitation to a threat actor unless the source evidence explicitly supports that linkage.

What should be done in the next 24 hours?

Identify exposed assets running affected vendor/product/version combinations. Treat as emergency remediation because CISA KEV status is present. Search available logs for exploit probes, errors, authentication anomalies, or suspicious child processes matching the vulnerability class. Open remediation tickets with affected assets, owners, evidence status, and detection coverage so decisions are traceable.

CISA KEVhighpublic exploit

CVE-2026-87886

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

Q: Is it in CISA KEV?

Yes. The supplied enrichment data lists CVE-2026-87886 in CISA KEV with 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.. KEV status should be monitored because it can change after initial disclosure or after exploitation becomes publicly confirmed.

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.

Published Sep 17, 2026Updated Sep 18, 2026Sources: NVD, Acronis (CNA), CISA, GitHub, SOCRadar CTI

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the scoring sources call it.

Exploitation

Confirmed

CISA KEV, listed Sep 16, 2026

EPSS

ahead of 0% of scored CVEs

Affects

Acronis

3 products listed

CVSS base

7.8

high

Remediation

The vendor's own words where we have them.

Upgrade Acronis Backup plugin for cPanel & WHM to a fixed release. Apply vendor patches per advisory and restrict external exposure of the affected component until patched.

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.

Federal deadline Sep 19, 2026 — in 1 day

First 24 hours

Ordered from the record's own fields — exposure first, because you cannot patch what you have not found.

Identify exposed assets running affected vendor/product/version combinations.
Treat as emergency remediation because CISA KEV status is present.
Search available logs for exploit probes, errors, authentication anomalies, or suspicious child processes matching the vulnerability class.

Affected scope

Vendor, product and version as the advisories word them.

Vendor	Product	Versions	Status
Acronis	Acronis Backup plugin for cPanel & WHM	unspecified to < 1.9.3.1021	Vulnerable
Acronis	Acronis Backup extension for Plesk	unspecified to < 1.8.11.638	Vulnerable
Acronis	Acronis Backup plugin for DirectAdmin	unspecified to < 1.2.3.238	Vulnerable

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Availability

High

Confidentiality

High

Integrity

High

Scope

Unchanged

Attack Complexity

Low

Attack Vector

Local

Privileges Req

Low

User Interaction

None

Every base score collected

Sources score independently and disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Source
7.8	CVSS 3.0	high	1.8	5.9	acronis.com (CNA), Acronis (CNA)

CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

What this weakness leads to

MITRE's own consequences and mitigations for the weakness class — the authority's wording, not guidance derived from the CVSS vector.

MITRE

CWE-276 · Incorrect Default Permissions

Read Application Data
Modify Application Data::

Mitigation: The architecture needs to access and modification attributes for files to only those users who actually require those actions.

Weakness & attack patterns

CWE-276

Attack patterns reported against this CVE. The ATT&CK techniques below are inferred from its weakness class.

CAPEC-127 · Directory IndexingCAPEC-81 · Web Logs TamperingCAPEC-1 · Accessing Functionality Not Properly Constrained by ACLs

T1574.010Hijack Execution Flow: ServicesFile Permissions Weakness
T1083File and Directory Discovery

CISA KEV details

CISA lists a CVE here once it has evidence of exploitation against real targets.

CISAThat month →

Listed

Sep 16, 2026

Federal deadline

Sep 19, 2026

in 1 day

Ransomware use

Unknown

CISA records ransomware use only for campaigns it has confirmed, so “Unknown” means unrecorded, not ruled out. The deadline binds US federal agencies; for everyone else it is a date to argue against.

Public exploit

Capability, not use: code existing is a different claim from anyone running it.

Repositories

1 of the 5 sampled are weaponized

Social mentions

Posts naming this CVE. Attention, not evidence of exploitation — it spikes on disclosure and decays whether or not anything is exploited.

19 more posts on this CVEShowing 5 of 24 · Who is discussing this CVE, and how loudlyUnlock free

Detection

Read off the CVSS vector and the weakness class. Starting points, not rules we have tested.

Monitor for scanner or exploit-pattern traffic after 7 public PoC repositories were reported.

Timeline

What happened to this CVE, newest first — with the readings a source repeats on a schedule counted underneath rather than listed.

2026
Added · CVSS 3.1 7.8 (AV:L)
Sep 18, 2026 · NVD
Initial · CVE published
Sep 17, 2026 · NVD
CVE published by NIST.
Sep 17, 2026 · SOCRadar CTI
Added to CISA KEV catalog
Sep 16, 2026 · CISA

Source activity

Readings a source repeats on a schedule, counted rather than listed.

2×TweetsSep 16, 2026 – Sep 17, 2026 · SOCRadar CTI
2×SvrsSep 16, 2026 – Sep 17, 2026 · SOCRadar CTI
1×CVE appeared in the Cve Trends.Sep 17, 2026 · SOCRadar CTI

References

4 on the record

security-advisory.acronis.com/advisories/SEC-10986
Vendor Advisory, NIST, Mitre
www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk
US Government Resource
www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk
US Government Resource
nvd.nist.gov/vuln/detail/CVE-2026-87886
Vendor Advisory

Coverage

9 stories from the feeds we poll

4 more reports on this CVEShowing 5 of 9 · Vendor research and security press coverageUnlock free

Elsewhere on this site

Acronisevery CVE for this vendor
September 2026what else CISA listed
Unclassifiedsame class
CWE-276other pages naming this weakness

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record1

What should defenders know first?

CVE-2026-87886 is Acronis Backup Incorrect Default Permissions Vulnerability, a high vulnerability affecting Acronis Backup plugin for cPanel & WHM, Acronis Backup extension for Plesk, Acronis Backup plugin for DirectAdmin from Acronis. The current evidence lists it in CISA KEV, and the exploit status is: Yes: CISA KEV signal present. Public exploit evidence is: 7 public PoC repositories reported; 1 marked weaponized in current dataset. The affected-version evidence is listed in the key facts and affected products tables. Defenders should first verify whether exposed or business-critical assets run those versions, then apply vendor patches or mitigations, restrict reachable attack surface, and preserve logs for detection review. CVSS 7.8 describes technical severity, while EPSS 0% helps estimate near-term exploit likelihood; neither replaces asset context. Unknown fields should remain explicit in tickets, and threat actor, IOC, victimology, or payload claims should not be added unless a cited source supports them. Monitor CISA KEV, vendor advisories, NVD changes, public PoC repositories, and internal telemetry for update triggers.