VulnerabilityPublished 12 Dec 2023Updated 7 Nov 2025

CVE-2023-5379: Red Hat JBoss Enterprise Application Platform 7.1 EUS for RHEL 7 · Unthrottled Resource Allocation

Affects Red Hat JBoss Enterprise Application Platform 7.1 EUS for RHEL 7Source CVE Database V5

Not known to be exploited · CVSS 7.5 High.

Data as of 26 Oct 2026, 09:15 UTC

CVSS 3.1 base score

7.5High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 1.0% chance of exploitation in 30 days – higher than 63% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: None
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 12 Dec 2023
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

AI-suggested

1. Apply official patches from Red Hat as soon as they become available to address the vulnerability in Undertow and mod_cluster components. 2. Review and tighten the max-header-size configuration in the ajp-listener to reasonable limits that prevent oversized headers without impacting legitimate traffic. 3. Implement monitoring and alerting on mod_cluster error states and backend instance health to detect early signs of exploitation or misconfiguration. 4. Use network-level controls such as firewalls or intrusion prevention systems to detect and block AJP requests with headers exceeding expected sizes. 5. Consider disabling or restricting AJP connectors if not required, or isolate them behind secure network segments to reduce exposure. 6. Conduct regular security assessments and penetration tests focusing on load balancer and backend communication protocols. 7. Educate operations teams about this vulnerability and ensure incident response plans include steps to handle mod_cluster-related DoS scenarios. 8. Evaluate alternative load balancing or proxy solutions if mod_cluster is critical and cannot be adequately secured.

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).

Impact

For European organizations, the primary impact of CVE-2023-5379 is the potential for denial of service against critical enterprise applications hosted on Red Hat JBoss EAP 7.1 on RHEL 7. This can disrupt business operations, degrade service availability, and potentially expose sensitive data through error states or misconfigurations. Industries such as finance, government, telecommunications, and manufacturing that rely on JBoss EAP for middleware services are particularly vulnerable. The disruption caused by mod_cluster marking backend instances as error workers can lead to load balancing failures and service outages, impacting end-users and business continuity. Additionally, the vulnerability could be leveraged as part of a larger attack chain to degrade defenses or distract security teams. Given the widespread use of Red Hat products in Europe and the critical role of JBoss EAP in enterprise Java applications, the threat poses a significant operational risk, especially in countries with large enterprise IT infrastructures and digital services dependent on these platforms.

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Exploitation evidence

What to do

Description

AI analysisMachine-generated, updated 7 Nov 2025, 11:28 UTC

Technical details

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