CVE-2026-91484: Access Control Flaw (CVSS 7.5)

Description

Vulnerability in Oracle Java SE (component: Java plugin). Supported versions that are affected are Oracle Java SE: 8u503 and 8u503-perf. Difficult to exploit vulnerability allows low privileged attacker with logon to the infrastructure where Oracle Java SE executes to compromise Oracle Java SE. While the vulnerability is in Oracle Java SE, attacks may significantly impact additional products (scope change). Successful attacks of this vulnerability can result in unauthorized creation, deletion or modification access to critical data or all Oracle Java SE accessible data as well as unauthorized access to critical data or complete access to all Oracle Java SE 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 7.5 (Confidentiality and Integrity impacts). CVSS Vector: (CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N).

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CVSS v3.1 Score

7.5

HIGH

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N

EPSS — Exploit Prediction

0.0011

Probability of exploitation

0.01%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-284 CWE-284

References

Other References

https://www.oracle.com/security-alerts/cpuoct2026.html

Frequently Asked Questions

What is CVE-2026-91484? +

Vulnerability in Oracle Java SE (component: Java plugin). Supported versions that are affected are Oracle Java SE: 8u503 and 8u503-perf. Difficult to exploit vulnerability allows low privileged attacker with logon to the infrastructure where Oracle Java SE executes to compromise Oracle Java SE. While the vulnerability is in Oracle Java SE, attacks may significantly impact additional products (scope change). Successful attacks of this vulnerability can result in unauthorized creation, deletion or modification access to critical data or all Oracle Java SE accessible data as well as unauthorized access to critical data or complete access to all Oracle Java SE 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 7.5 (Confidentiality and Integrity impacts). CVSS Vector: (CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N). It has a CVSS v3.1 base score of 7.5 (HIGH).

How severe is CVE-2026-91484? +

CVE-2026-91484 has a CVSS v3.1 score of 7.5 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0011, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-91484? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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