VulnerabilityPublished 12 Mar 2026

CVE-2026-3234: Red Hat Enterprise Linux 10 · CRLF Injection

Affects Red Hat Enterprise Linux 10Source CVE Database V5

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Not known to be exploited · CVSS 4.3 Medium.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score

4.3Medium

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

EPSS: 0.3% chance of exploitation in 30 days – higher than 26% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

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

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

Attack Vector: Adjacent: The vulnerable component is bound to the network stack, but the attack is limited at the protocol level to a logically adjacent topology. This can mean an attack must be launched from the same shared physical (e.g., Bluetooth or IEEE 802.11) or logical (e.g., local IP subnet) network, or from within a secure or otherwise limited administrative domain (e.g., MPLS, secure VPN to an administrative network zone).
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: None: There is no loss of confidentiality within the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on 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 Mar 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: 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 30 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.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity 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

Affected software

Product	Affected	Fixed in
Red Hat Enterprise Linux 10mod_proxy_cluster	Affected–	Fixed in–
Red Hat Enterprise Linux 9mod_proxy_cluster	Affected–	Fixed in–
Red Hat JBoss Core Servicesjbcs-httpd24-mod_proxy_cluster	Affected–	Fixed in–
Red Hat JBoss Core Servicesmod_proxy_cluster	Affected–	Fixed in–

AI-suggested

Apply patches from Red Hat as soon as they become available to address the CRLF injection vulnerability in mod_proxy_cluster.
Restrict network access to the MCMP protocol port using firewalls, network segmentation, or access control lists to limit exposure to trusted hosts only.
Monitor network traffic to the MCMP port for unusual or unexpected requests that could indicate exploitation attempts.
Implement strict input validation and sanitization in any custom integrations or scripts interacting with mod_proxy_cluster or the MCMP protocol.
Review and harden cluster configuration management processes to detect and prevent unauthorized changes.
Employ intrusion detection or prevention systems capable of identifying CRLF injection patterns in network traffic.
Conduct regular security audits and vulnerability assessments focusing on internal network services and protocol ports.
Educate system administrators about the risks of CRLF injection and the importance of securing internal communication protocols.

Description

A flaw was found in mod_proxy_cluster. This vulnerability, a Carriage Return Line Feed (CRLF) injection in the decodeenc() function, allows a remote attacker to bypass input validation. By injecting CRLF sequences into the cluster configuration, an attacker can corrupt the response body of INFO endpoint responses. Exploitation requires network access to the MCMP protocol port, but no authentication is needed.

Impact

The primary impact of CVE-2026-3234 is on the integrity of response data from the mod_proxy_cluster INFO endpoint. By injecting CRLF sequences, attackers can corrupt response bodies, potentially leading to HTTP response splitting or cache poisoning attacks in systems that rely on these responses. While confidentiality and availability are not directly affected, the integrity compromise could facilitate further exploitation or mislead system administrators and automated tools. Since exploitation requires network access to the MCMP protocol port, the threat is more significant in environments where this port is exposed or insufficiently protected. Organizations with critical infrastructure or services relying on mod_proxy_cluster for load balancing or proxying may face operational risks if attackers manipulate cluster configurations or monitoring data. The absence of authentication requirements increases the risk from insider threats or lateral movement within compromised networks. Although no active exploits are known, the vulnerability could be leveraged in targeted attacks against enterprise Linux environments, especially in sectors with high reliance on Red Hat Enterprise Linux 10.

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 12 Mar 2026, 14:01 UTC

Technical details

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