Exploited CVEs / Oracle / CVE-2023-21839

CVE-2023-21839

Oracle WebLogic Server Unspecified Vulnerability. Exploitation in the wild is confirmed by CISA, not predicted. Federal agencies were required to remediate by 2023-05-22 (that deadline has passed); treat that date as the outer bound for your own environment. The fix is in the vendor advisory: Oracle Critical Patch Updates, linked below.

Risk summary

HighCISA KEV

7.5

CVSS base

100%

EPSS exploit probability

High

Severity

2023-05-01

Added to KEV

2023-05-22 (past due)

CISA due date

Actively exploited Oracle WebLogic Server vulnerability, High severity, CVSS 7.5. Added to the CISA KEV catalog 2023-05-01.

Senserva AI read on CVE-2023-21839 CISA required action Official fix for CVE-2023-21839 Admin questions

Senserva AI Opinion for CVE-2023-21839

Oracle WebLogic Server can be compromised by an unauthenticated attacker over its T3 and IIOP protocols, and the 100% EPSS score tells you scanning for it never stopped. WebLogic sits under large ERP and middleware stacks, so a compromised instance is deep inside the application tier from the first moment. It is rated High Severity (CVSS 7.5) and was confirmed exploited in May 2023.

Do this: Apply Oracle's patch and disable or firewall T3 and IIOP on any WebLogic server that does not require them.

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

Senserva AI Opinion and rich prompt for CVE-2023-21839

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

I run IT security. Facts for CVE-2023-21839, an actively exploited vulnerability (source: https://senserva.com/cve/CVE-2023-21839.html, data from CISA KEV, FIRST.org EPSS, NVD, refreshed twice a day (5 AM and 3 PM US Central)):
- CVE-2023-21839: Oracle WebLogic Server Unspecified Vulnerability
- Affected: Oracle WebLogic Server
- Severity: High, CVSS 7.5; EPSS 30-day exploitation probability 100%
- Added to CISA KEV: 2023-05-01; federal remediation due 2023-05-22
- Ransomware-linked: no
- CISA required action: Apply updates per vendor instructions.
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 now

Exploited in the wild: confirmed by the CISA KEV catalog, not predicted.

The fix ships from the vendor: Oracle Critical Patch Updates.

Do this now: Federal remediation deadline 2023-05-22; treat it as your outer bound. Patch now and verify deployment 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-2023-21839

Published: 2023-05-01
Last revised: 2023-05-01
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

2023-05-01 added to the CISA KEV catalog by CISA
2026-07-17 CVSS 0.0 to 7.5; EPSS first scored at 99.8%

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: 2023-05-22 (past due).

Apply updates per vendor instructions.

Official fix for CVE-2023-21839

The authoritative fix and affected-version list are published by the vendor. Find the WebLogic Server advisory on Oracle Critical Patch Updates.

Oracle Critical Patch Updates CISA KEV entry

Common questions about CVE-2023-21839

Is CVE-2023-21839 actively exploited?

Yes. CVE-2023-21839 was added to the CISA Known Exploited Vulnerabilities (KEV) catalog on 2023-05-01, which means exploitation in the wild has been confirmed, not predicted. Its EPSS 30-day exploitation probability is 100%.

What is the CISA deadline and required action for CVE-2023-21839?

CISA set the federal (BOD 22-01) remediation due date at 2023-05-22, which has passed; treat any unremediated system as overdue. The verbatim required action: Apply updates per vendor instructions.

What fixes CVE-2023-21839?

The authoritative fix is in the vendor advisory: see Oracle Critical Patch Updates for the patched WebLogic Server 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-2023-21839?

Yes. This page includes a free, ready-to-paste AI prompt containing CVE-2023-21839'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

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All Oracle exploited CVEs on one page: Oracle 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.