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

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).

Published: 2023-12-12 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2023-5379 is rated Moderate Risk (51.4/100): CVSS High severity, with medium exploitation likelihood (EPSS 1.02%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2023-5379

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.16% 1.02% +0.85%
2 2026-04-25 0.14% 0.16% +0.02%
3 2025-11-21 — 0.14% —

Full EPSS history (11 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2023-5379

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 3.6 [email protected]
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]

Weakness enumeration for CVE-2023-5379

OS Trackers for CVE-2023-5379

vendor priority summary link
debian not yet assigned CVE-2023-5379 not yet assigned priority: Debian including 1 source packages (undertow), 2 status rows across 2 suites (forky, sid): resolved 2. https://security-tracker.debian.org/tracker/CVE-2023-5379
redhat medium — https://access.redhat.com/security/cve/CVE-2023-5379
ubuntu medium CVE-2023-5379 medium priority: Ubuntu including 1 source packages (undertow), 12 status rows across 12 suites (bionic, focal, jammy, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): needs-triage 7, ignored 3, DNE 2. https://ubuntu.com/security/CVE-2023-5379

Affected software / configurations for CVE-2023-5379

Vendor Product Version Raw CPE
redhat jboss_enterprise_application_platform — cpe:2.3:a:redhat:jboss_enterprise_application_platform:-:*:*:*:text-only:*:*:*
redhat jboss_enterprise_application_platform 7.0.0 cpe:2.3:a:redhat:jboss_enterprise_application_platform:7.0.0:*:*:*:*:*:*:*
redhat single_sign-on 7.0 cpe:2.3:a:redhat:single_sign-on:7.0:*:*:*:*:*:*:*
redhat undertow — cpe:2.3:a:redhat:undertow:-:*:*:*:*:*:*:*

References for CVE-2023-5379

cvelogic Threat Intelligence