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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Red Hat | Red Hat build of Apache Camel for Spring Boot 4 | — | — |
| Red Hat | Red Hat Enterprise Linux 10 | — | — |
| Red Hat | Red Hat Enterprise Linux 8 | — | — |
| Red Hat | Red Hat Enterprise Linux 9 | — | — |
| Red Hat | Red Hat Fuse 7 | — | — |
| Red Hat | Red Hat JBoss Enterprise Application Platform 7 | — | — |
| Red Hat | Red Hat JBoss Enterprise Application Platform 8 | — | — |
| Red Hat | Red Hat JBoss Enterprise Application Platform Expansion Pack | — | — |
| Red Hat | Red Hat Single Sign-On 7 | — | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | undertow | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | undertow | No fix yet | — |
| Ubuntu 26.04 LTS | undertow | No fix yet | — |
Show 5 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 24.04 LTS | undertow | No fix yet | — |
| Ubuntu Pro 22.04 LTS | undertow | No fix yet | — |
| Ubuntu Pro 20.04 LTS | undertow | No fix yet | — |
| Ubuntu Pro 18.04 LTS | undertow | No fix yet | — |
| Ubuntu Pro 16.04 LTS | undertow | No fix yet | — |
Advisories 1
- WID-SEC-2026-3099 Red Hat Undertow: Schwachstelle ermöglicht Denial of Service BSI CERT-Bund (WID) · Aug 30, 2026
References
- https://access.redhat.com/security/cve/CVE-2026-81624 vdb-entry
- RHBZ#2524868 issue-tracking