KEV Lag Tracker → CVE-2026-87886. Data verified against the official CISA KEV catalog and the National Vulnerability Database.
CISA added CVE-2026-87886 (Acronis Backup) to the Known Exploited Vulnerabilities catalog on September 16, 2026. CISA listed it as actively exploited 1 day before its NVD publication date — exploitation was confirmed at or before public disclosure. A KEV listing is CISA’s official confirmation that a vulnerability is being exploited in the wild.
The Record
| CVE | CVE-2026-87886 |
| Vendor / product | Acronis Backup |
| Vulnerability | Acronis Backup Incorrect Default Permissions Vulnerability |
| CVSS base score | 7.8 |
| NVD publication date | September 17, 2026 |
| Added to CISA KEV | September 16, 2026 |
| Lag (public → KEV listing) | -1 days |
| Federal patch deadline | September 19, 2026 |
| Known ransomware use | No |
Measured against the 1729 entries in our tracker with verified publication dates, CVE-2026-87886 was flagged faster than 96% of them.
What CISA Reported
CISA describes the flaw as follows: “Acronis Backup plugin for cPanel & WHM and extension for Plesk contains an incorrect default permissions vulnerability that could allow for privilege escalation.”
Federal Patch Deadline
Under Binding Operational Directive rules, U.S. federal agencies must remediate CVE-2026-87886 by September 19, 2026 — a 3-day remediation window from the KEV listing date. Private organizations are not bound by that deadline; CISA treats it as the benchmark for how urgently a confirmed-exploited flaw should be patched.
What EPSS Forecast Before the Confirmation
EPSS had no score for CVE-2026-87886 on the day before CISA confirmed exploitation. That normally means the CVE had not yet been published when it was already being exploited — a case no forecast could have flagged. Its current EPSS probability is 0.23%. See the EPSS accuracy analysis for how often this happens.
How This Compares
We do not yet track enough Acronis entries to publish a vendor median (the threshold is five with verified publication dates), so the reference here is the catalog as a whole:
| Across all tracked KEV entries | Value |
|---|---|
| Entries with verified publication dates | 1729 |
| Median lag (disclosure → KEV listing) | 245 days |
| Exploited within 7 days of disclosure | 24% |
| Tied to known ransomware campaigns | 19% |
Defense guide: How to Detect Zero-day Vulnerability: Attack Chain & Defense — detection signals, attack chain and response steps for this class of attack.
Frequently Asked Questions
What is CVE-2026-87886?
CVE-2026-87886 is a vulnerability in Acronis Backup (Acronis Backup Incorrect Default Permissions Vulnerability) that CISA added to its Known Exploited Vulnerabilities catalog on September 16, 2026. A KEV listing is CISA’s official confirmation that the flaw is being exploited in the wild.
How long was CVE-2026-87886 public before CISA confirmed exploitation?
1 days before its NVD publication date — CISA listed it as exploited at or before the vulnerability was formally published, which is the signature of a zero-day.
What is the federal patch deadline for CVE-2026-87886?
U.S. federal agencies must remediate CVE-2026-87886 by September 19, 2026, a 3-day window from the KEV listing date. Private organizations are not bound by that deadline, but CISA treats it as the benchmark for how urgently a confirmed-exploited flaw should be patched.
Is CVE-2026-87886 used in ransomware campaigns?
CISA has not flagged CVE-2026-87886 as known to be used in ransomware campaigns. That field reflects confirmed campaign use, not the absence of risk.
Is a -1-day lag typical?
The median across all 1729 KEV entries we track with verified publication dates is 245 days, so CVE-2026-87886 is below the catalog median.
Related Coverage
- Critical Microsoft SharePoint Flaw CVE-2026-50522 (CVSS 9.8) Added to CISA KEV (July 2026)
- WordPress’s CVE-2026-63030 Was Exploited in 4 Days — Well Under Its 420-Day Median (July 2026)
Primary Sources
- CISA Known Exploited Vulnerabilities Catalog — the official listing that confirms active exploitation, and the source of the KEV date on this page.
- NVD — CVE-2026-87886 — publication date, CVSS score and the full technical record.
- Vendor advisory — security-advisory.acronis.com — Acronis’s own disclosure, with the affected versions and the fix.
How We Track This
This page is generated from our CISA KEV Lag Tracker, which syncs the official CISA KEV catalog daily and records the date each CVE is added. For every entry we retrieve the original NVD publication date and compute the lag in calendar days. No date or figure on this page is estimated or taken from a third-party source — they come directly from CISA and NVD records. Free to cite with attribution to CVEDaily (CC BY 4.0).