How do I check whether I am affected by CVE-2026-91461?

- Run `java -version` and compare against the affected releases: Java SE 8u503, 11.0.32.1, 17.0.20.1, 21.0.12.1, 25.0.4.1, 27; GraalVM for JDK 17.0.20.1 and 21.0.12.1; GraalVM Enterprise 21.3.19.1.1.

What is the fix for CVE-2026-91461?

- Move Oracle Java SE to a patched release from Oracle's April 2026 Critical Patch Update, such as `21.0.12.1` or `25.0.4.1`, per the vendor advisory. - Move Oracle GraalVM for JDK to a patched build from the same update. - Oracle's advisory for this CVE was not in the sources, so the exact fixed build per line is unknown.

Who is not affected by CVE-2026-91461?

Not affected if: default-config.

Live › vulnerability › CVE-2026-91461

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low3.7Runtime

Oracle Java SE JSSE: TLS flaw lets unauthenticated network attacker modify some data

A flaw in the JSSE component of Oracle Java SE and Oracle GraalVM lets an unauthenticated attacker over TLS write some accessible data. The attack is hard to carry out and works by supplying data to Java APIs, such as through a web service.

Summary written from the sources below. Check the originals before acting.

CVSS 3.x

3.7

low

scored by [email protected]

known so far3 of 6

missing: versions, primary source, exploitation

First public: Oct 20, 2026 UTC
Last modified: Oct 21, 2026
Status: open
Known exploitation: None reported
Public exploit: None on GitHub
EPSS: not scored

First seen by InfraStack 2026-10-23 21:57 UTC. All times on this page are UTC.

Why it is low, and not just CVSS

Likelihood → · Impact ↓

critical

high

medium

high

medium

low

medium

low

Exploited: No reports yet.
Needs login: No.
Needs a special setup: Not known from the sources.
Reachable from: internet.
Worst case: Attacker modifies some data the Java application can access.
CVSS said: 3.7. The facts above say medium; we keep the sources' low until an analyst looks.

Who is affected

Teams running Oracle Java SE or Oracle GraalVM runtimes that expose TLS-based Java services, such as web services that parse untrusted input through JSSE APIs. Systems that run only non-affected releases or do not expose Java services to the network can skip it.

Know the next one before it finds you.

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Live › vulnerability › CVE-2026-91461

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low3.7Runtime

Oracle Java SE JSSE: TLS flaw lets unauthenticated network attacker modify some data

Summary written from the sources below. Check the originals before acting.

CVSS 3.x

3.7

low

scored by [email protected]

known so far3 of 6

missing: versions, primary source, exploitation

First public: Oct 20, 2026 UTC
Last modified: Oct 21, 2026
Status: open
Known exploitation: None reported
Public exploit: None on GitHub
EPSS: not scored

First seen by InfraStack 2026-10-23 21:57 UTC. All times on this page are UTC.

Why it is low, and not just CVSS

Likelihood → · Impact ↓

critical

high

medium

high

medium

low

medium

low

Exploited: No reports yet.
Needs login: No.
Needs a special setup: Not known from the sources.
Reachable from: internet.
Worst case: Attacker modifies some data the Java application can access.
CVSS said: 3.7. The facts above say medium; we keep the sources' low until an analyst looks.

Who is affected

Know the next one before it finds you.

Add to Slack

Oracle Java SE JSSE: TLS flaw lets unauthenticated network attacker modify some data

Why it is low, and not just CVSS

Who is affected

Know the next one before it finds you.

Oracle Java SE JSSE: TLS flaw lets unauthenticated network attacker modify some data

Why it is low, and not just CVSS

Who is affected

Know the next one before it finds you.

How to check

The fix

Who had it, and when

What the sources say, verbatim

Sources