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Oracle Java SE EUVDEUVD-2026-106712

| CVE-2026-91464 MEDIUM
Use After Free (CWE-416)
2026-10-20 secalert_us@oracle.com GHSA-gj42-xjcm-wrr9
5.3
CVSS 3.1 · Vendor: oracle
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Host malicious applet/Web Start app
  2. Exploit
    Lure victim to load untrusted code
  3. Execution
    Abuse JGSS to bypass sandbox
  4. Impact
    Read confidential JVM-accessible data

Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Memory lifecycle management
MITRE ATT&CK

2 techniques across 2 tactics: Execution, Privilege Escalation

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

Applies ONLY to Java client deployments that load and run untrusted code (sandboxed Java Web Start applications or sandboxed Java applets, e.g. code from the internet) and rely on the Java sandbox for security; it does NOT apply to server deployments that run only trusted, administrator-installed code. Exploitation further requires human interaction from a user other than the attacker (UI:R) - the victim must load/run the attacker's content - and Oracle rates it difficult to exploit (AC:H). The principal limiting factor is that the vulnerable configuration (browser applets / Web Start) is deprecated and disabled or absent in most modern environments, sharply reducing the realistically attackable population despite the ubiquity of Java itself.

Impact

Despite a C:H confidentiality rating, the real-world risk is LOW-to-MODERATE and well below what the 'critical data access' phrasing might suggest. The CVSS 3.1 base score is only 5.3 (Medium) because exploitation is gated by three independent limiters in the vector: AC:H (Oracle explicitly calls it 'difficult to exploit'), UI:R (requires a victim other than the attacker to act), and S:U (no scope change). PR:N confirms no authentication is needed, but that is offset by the requirement that the target be running the increasingly rare sandboxed applet/Java Web Start configuration. No EPSS score, CISA KEV listing, or public POC is present in the provided data, so there is no evidence of active or imminent exploitation. The signals are internally consistent rather than conflicting: a high-confidentiality-impact but hard-to-exploit, interaction-dependent client-side flaw. The main caveat is that the product (Java SE) is ubiquitous while the vulnerable deployment mode (untrusted sandboxed code) is largely deprecated - raw prevalence overstates the attackable population. CWE is N/A and no EPSS value was supplied, so quantitative exploitation probability could not be factored in.

Exploit ScenarioDerived

An attacker hosts a malicious Java applet or Java Web Start application on an internet site and lures a victim into loading it in a browser/client still configured to run untrusted sandboxed Java. When the victim runs the code, it abuses the JGSS component to escape sandbox confidentiality controls and read sensitive data accessible to the JVM. No public exploit code was identified in the provided data, and the AC:H rating indicates the attack is technically difficult to reliably reproduce.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
No patch listed yet 0.3% exploitation probability (EPSS)

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AnalysisAIv1 – Oct 21, 2026

Unauthorized access to sensitive data in Oracle Java SE (8u503/8u503-perf, 11.0.32.1, 17.0.20.1, 21.0.12.1, 25.0.4.1, 27), Oracle GraalVM for JDK (17.0.20.1, 21.0.12.1) and Oracle GraalVM Enterprise Edition (21.3.19.1.1) becomes possible when a Java client runtime executes attacker-supplied code inside the sandbox - typically a sandboxed Java Web Start application or applet loaded from the internet - and the JGSS component fails to enforce an intended security boundary. The CVSS 3.1 score is 5.3 (AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N): reachable over the network by an unauthenticated attacker, but gated by required human interaction and explicitly rated difficult to exploit, with confidentiality-only impact and no integrity or availability effect. No public exploit code or CISA KEV entry is associated with this CVE at time of analysis, and realistic exposure is sharply limited because the vulnerable configuration (browser applets and Web Start) is deprecated and disabled or absent in most modern environments; server deployments running only administrator-installed trusted code are explicitly out of scope.

RemediationAI

Apply the Oracle Critical Patch Update for October 2026 (https://www.oracle.com/security-alerts/cpuoct2026.html) and move each affected train - JDK 8u503/8u503-perf, 11.0.32.1, 17.0.20.1, 21.0.12.1, 25.0.4.1, 27, GraalVM for JDK 17.0.20.1/21.0.12.1, and GraalVM Enterprise 21.3.19.1.1 - to the corresponding CPU-fixed build; patch availability is confirmed via the vendor advisory, though the specific fixed version strings are not enumerated in the supplied data. Because the flaw is only reachable through sandboxed untrusted client code, the highest-value compensating control is to eliminate that execution path: keep the Java browser plug-in uninstalled, remove or block JNLP/Web Start handlers (.jnlp MIME type), and enforce the modern deployment defaults that disable applet and Web Start launch (for example the deployment.security.* and deployment.webstart settings, plus removal of any Exception Site List entries) - the trade-off is that any remaining legacy intranet applet or JNLP application will stop working and must be re-platformed. Additionally, restrict client workstations from reaching untrusted JNLP/applet content at the proxy and enforce click-to-run prompts, accepting the residual risk that user interaction (UI:R) is the only barrier for already-visited malicious sites; patching remains the only control that removes the defect itself.

Affected VersionsENISA

Oracle Java SE 17.0.20.1
Oracle Java SE 27
Oracle GraalVM Enterprise Edition 21.3.19.1.1
Oracle GraalVM for JDK 17.0.20.1
Oracle Java SE 25.0.4.1
Oracle Java SE 21.0.12.1
Oracle Java SE 8u503
Oracle GraalVM for JDK 21.0.12.1
Oracle Java SE 8u503-perf
Oracle Java SE 11.0.32.1

Affected Packages

euvd oracle_graalvm_enterprise_edition no fix
euvd oracle_graalvm_for_jdk no fix
euvd oracle_java_se no fix

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 3 packages in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

JGSS is the Java binding of the Generic Security Services API (GSS-API), the framework behind Kerberos v5 and SPNEGO authentication inside the JDK; it supplies the credential and context establishment machinery that sandboxed client code can reach. The vulnerability sits in that component and, per Oracle's pre-patch advisory convention, the precise root cause is withheld - the feed carries no CWE mapping (CWE: N/A), though the accompanying 'Authentication Bypass' tag and the confidentiality-only, no-integrity/no-availability profile point to a failure to enforce an intended access-control boundary rather than memory corruption. Exploitation is meaningful only in the classic Java sandbox model, where the SecurityManager and the applet/Web Start launcher confine untrusted remote code; a bypass lets that code read data outside its intended permission set. Oracle scores it AC:H (difficult, non-deterministic to trigger) and UI:R (the victim must load the malicious content), and the attack surface depends entirely on a client runtime that still permits applet or JNLP execution - a stack that was removed or disabled by default in JDK 11+ and later releases, which is the dominant mitigating factor despite Java's ubiquity. Affected CPEs span the oracle:jdk 8u503, 11.0.32.1, 17.0.20.1, 21.0.12.1, 25.0.4.1 and 27 trains plus oracle:graalvm for JDK 17/21 and GraalVM Enterprise 21.3.19.1.1.

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Severity by source

Vendor (oracle) PRIMARY 5.3 MEDIUM
AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N
vuln.today AI 5.3 MEDIUM

Remote unauthenticated (AV:N/PR:N) but hard to exploit (AC:H) and victim must run untrusted code (UI:R); confidentiality-only disclosure so C:H, I:N, A:N, no scope change.

3.1 AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N
4.0 AV:N/AC:H/AT:N/PR:N/UI:A/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

Primary rating from Vendor (oracle).

CVSS VectorVendor: oracle

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

DescriptionCVE.org

Vulnerability in the Oracle Java SE, Oracle GraalVM for JDK, Oracle GraalVM Enterprise Edition product of Oracle Java SE (component: JGSS). Supported versions that are affected are Oracle Java SE: 8u503, 8u503-perf, 11.0.32.1, 17.0.20.1, 21.0.12.1, 25.0.4.1, 27; Oracle GraalVM for JDK: 17.0.20.1 and 21.0.12.1; Oracle GraalVM Enterprise Edition: 21.3.19.1.1. Difficult to exploit vulnerability allows unauthenticated attacker with network access via multiple protocols to compromise Oracle Java SE, Oracle GraalVM for JDK, Oracle GraalVM Enterprise Edition. Successful attacks require human interaction from a person other than the attacker. Successful attacks of this vulnerability can result in unauthorized access to critical data or complete access to all Oracle Java SE, Oracle GraalVM for JDK, Oracle GraalVM Enterprise Edition accessible data. Note: This vulnerability applies to Java deployments, typically in clients running sandboxed Java Web Start applications or sandboxed Java applets, that load and run untrusted code (e.g., code that comes from the internet) and rely on the Java sandbox for security. This vulnerability does not apply to Java deployments, typically in servers, that load and run only trusted code (e.g., code installed by an administrator). CVSS 3.1 Base Score 5.3 (Confidentiality impacts). CVSS Vector: (CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N).

Threat Intelligence Overview

EPSS Score
0.3%
Top 80% exploitable
Prevalence
Ubiquitous
Oracle Java SE is among the most widely deployed runtimes worldwide
Data Quality
4 sources
Confidence: Medium

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.3%
Patch available No
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation· derived
None
System Exposure· derived
Open
Automatable· derived
No
Human Impact· derived
Medium

Priority Score

26
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +26
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Authentication bypass attacks exploit flaws in the verification mechanisms that control access to systems and applications.

Use-after-free vulnerabilities occur when a program continues to access memory through a pointer after that memory has been deallocated.

Memory corruption occurs when a program writes data beyond the boundaries of allocated memory regions or accesses memory in unintended ways, violating the integrity of the process's address space.

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