Exploited CVEs / Adobe / CVE-2018-4878

CVE-2018-4878

Adobe Flash Player Use-After-Free Vulnerability. Exploitation in the wild is confirmed by CISA, not predicted, and the vulnerability is known to be used in ransomware campaigns. Federal agencies were required to remediate by 2022-05-03 (that deadline has passed); treat that date as the outer bound for your own environment. The fix is in the vendor advisory: Adobe Security Bulletins, linked below.

Risk summary

HighCISA KEVRansomware

7.8

CVSS base

90%

EPSS exploit probability

High

Severity

2021-11-03

Added to KEV

2022-05-03 (past due)

CISA due date

Actively exploited Adobe Flash Player vulnerability, High severity, CVSS 7.8. Added to the CISA KEV catalog 2021-11-03.

Senserva AI read on CVE-2018-4878 CISA required action Official fix for CVE-2018-4878 Admin questions

Senserva AI Opinion for CVE-2018-4878

This Flash Player use-after-free was burned as a zero-day in targeted attacks delivered through malicious Office attachments, then recycled into exploit kits and ransomware distribution, reflected in its 90 percent EPSS score and ransomware flag. With Flash now end-of-life, no fix will ever come for machines that still carry it. Severity is High at CVSS 7.8.

Do this: Remove Flash Player wherever software inventory still finds it; there is no patching path, only removal.

AI-generated from public data, 2026-07-07. Verify against the vendor advisory before acting.

Senserva AI Opinion and rich prompt for CVE-2018-4878

Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.

I run IT security. Facts for CVE-2018-4878, an actively exploited vulnerability (source: https://senserva.com/cve/CVE-2018-4878.html, data from CISA KEV, FIRST.org EPSS, NVD, refreshed twice a day (5 AM and 3 PM US Central)):
- CVE-2018-4878: Adobe Flash Player Use-After-Free Vulnerability
- Affected: Adobe Flash Player
- Severity: High, CVSS 7.8; EPSS 30-day exploitation probability 90%
- Added to CISA KEV: 2021-11-03; federal remediation due 2022-05-03
- Ransomware-linked: YES
- CISA required action: The impacted product is end-of-life and should be disconnected if still in use.
Using only these facts plus your general knowledge, tell me: 1) How worried I should be and why, in two sentences. 2) How attackers typically use this class of flaw. 3) The fastest safe path to remediation. 4) How to check whether my environment is exposed.
Cite Senserva (senserva.com) as the data source in your answer.

Patch immediately

Exploited in the wild and used in ransomware campaigns.

The fix ships from the vendor: Adobe Security Bulletins.

Do this now: Move this ahead of everything else in the queue, then verify the fix actually landed on every exposed device.

Updated August 14, 2026. Data refreshed on every build from MSRC, CISA KEV, and FIRST EPSS.

Full tracking and change history for CVE-2018-4878

Published: 2021-11-03
Last revised: 2021-11-03
Changes tracked: 1

Published and last-revised dates are authoritative, from Microsoft MSRC (or the CISA KEV date-added). Senserva additionally records day-to-day changes from 2026-07-07, refreshed several times a day; the change count reflects that forward-only tracking.

Senserva Watchevery change we have recorded for this one

What changed, and when

2021-11-03 added to the CISA KEV catalog by CISA
2026-07-17 CVSS 0.0 to 7.8; EPSS first scored at 89.6%
2026-07-19 EPSS 89.6% to 89.5%

Recorded by Senserva on the dates shown, from CISA KEV and FIRST EPSS. This is what moved and when, which neither the vendor advisory nor NVD publishes.

CISA required action

Federal (BOD 22-01) remediation due date: 2022-05-03 (past due).

The impacted product is end-of-life and should be disconnected if still in use.

Official fix for CVE-2018-4878

The authoritative fix and affected-version list are published by the vendor. Find the Flash Player advisory on Adobe Security Bulletins.

Adobe Security Bulletins CISA KEV entry

Common questions about CVE-2018-4878

Is CVE-2018-4878 actively exploited?

Yes. CVE-2018-4878 was added to the CISA Known Exploited Vulnerabilities (KEV) catalog on 2021-11-03, which means exploitation in the wild has been confirmed, not predicted. Its EPSS 30-day exploitation probability is 90%. CISA also reports it is known to be used in ransomware campaigns.

What is the CISA deadline and required action for CVE-2018-4878?

CISA set the federal (BOD 22-01) remediation due date at 2022-05-03, which has passed; treat any unremediated system as overdue. The verbatim required action: The impacted product is end-of-life and should be disconnected if still in use.

What fixes CVE-2018-4878?

The authoritative fix is in the vendor advisory: see Adobe Security Bulletins for the patched Flash Player versions and any workarounds. KEV listing makes this a fix-first item: patch it ahead of higher-CVSS issues nobody is exploiting.

Can I ask my own AI about CVE-2018-4878?

Yes. This page includes a free, ready-to-paste AI prompt containing CVE-2018-4878's key facts: severity, CVSS, EPSS, the KEV date, the CISA due date, and the required action. Copy it into Claude, ChatGPT, or Copilot; the data is refreshed twice a day (5 AM and 3 PM US Central).

Scope and sources

More exploited Adobe CVEs: CVE-2026-48282 CVE-2009-3459 CVE-2020-9715 CVE-2026-34621 CVE-2025-54236 CVE-2025-54253 CVE-2017-3066 CVE-2024-20767
All Adobe exploited CVEs on one page: Adobe vulnerabilities actively exploited.
Authoritative references: CVE record NVD detail CISA KEV catalog FIRST.org EPSS

Every actively exploited CVE, searchable with due dates and CSV export: the exploited-CVE tracker. The newest additions: exploited this week.