---
id: "CVE-2026-91373"
kind: "vulnerability"
aliases: ["CVE-2026-91373"]
title: "Java SE JSSE: unauthenticated TLS input can partly crash the runtime"
severity: "medium"
cvss: 5.3
epss: 0.00385
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["graalvm", "java", "jvm", "runtime", "self-hosted", "tls"]
not_affected_if: ["no-network-exposure", "non-affected-version"]
published_at: "2026-10-20T22:20:40+00:00"
first_seen_at: "2026-10-23T21:57:26+00:00"
updated_at: "2026-10-25T12:38:52+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-91373", "first_seen_at": "2026-10-23T21:57:26+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-91373", "first_seen_at": "2026-10-25T12:38:52+00:00"}]
---

# Java SE JSSE: unauthenticated TLS input can partly crash the runtime

A flaw in the JSSE TLS component of Oracle Java SE lets a remote, unauthenticated attacker over TLS cause a partial denial of service. The sources score it as availability-only impact with no confidentiality or integrity loss.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Run `java -version` and compare against the affected builds: Java SE 8u503, 11.0.32.1, 17.0.20.1, 21.0.12.1, 25.0.4.1, GraalVM for JDK 17.0.20.1 and 21.0.12.1, GraalVM Enterprise 21.3.19.1.1.
- Check whether the service exposes TLS endpoints that parse data through JSSE APIs, such as a web service consuming external input.

## Fix

- Move Java SE to the fixed release for your line (the sources do not list the patched version numbers; check Oracle's Critical Patch Update advisory).
- Upgrade GraalVM for JDK or GraalVM Enterprise to the patched build for your line.

## Timeline

- 2026-10-23T21:57:26+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-91373
- 2026-10-25T12:38:52+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-91373

## From the sources

Vulnerability in Oracle Java SE (component: JSSE).  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; Oracle GraalVM for JDK: 17.0.20.1 and  21.0.12.1; Oracle GraalVM Enterprise Edition: 21.3.19.1.1. Easily exploitable vulnerability allows unauthenticated attacker with network access via TLS to compromise Oracle Java SE.  Successful attacks of this vulnerability can result in unauthorized ability to cause a partial denial of service (partial DOS) of Oracle Java SE. Note: This vulnerability can be exploited by using APIs in the specified Component, e.g., through a web service which supplies data to the APIs. This vulnerability also 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. CVSS 3.1 Base Score 5.3 (Availability impacts).  CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L).

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_