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Linux Distros Unpatched Vulnerability : CVE-2026-49844

medium Nessus Plugin ID 326435

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Synopsis

The Linux/Unix host has one or more packages installed with a vulnerability that the vendor indicates will not be patched.

Description

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

 - Improper encoding of non-finite floating-point values during MapMessage JSON serialization in Apache Log4j API produces output that is not valid JSON. This issue affects Apache Log4j API versions 2.13.1 through 2.25.4 and version 2.26.0. The fix for CVE-2026-34481 did not cover all code paths: when a MapMessage contains a non-finite IEEE 754 value (NaN, Infinity, or -Infinity), MapMessage.asJson() emits the corresponding bare token. RFC 8259 does not permit these tokens, so a conformant parser rejects the resulting document. The defect is reachable only when both of the following conditions hold: * The application uses the message resolver https://logging.apache.org/log4j/2.x/manual/json-template- layout.html#event-template-resolver-message of JsonTemplateLayout or any other layout that relies on MapMessage.asJson() or MapMessage.getFormattedMessage(new String[]{JSON}). * The application logs a MapMessage that contains an attacker-controlled floating-point value. An attacker who can supply a non- finite value can cause the affected layout to emit malformed JSON, which may corrupt the enclosing log record or disrupt downstream log ingestion and parsing. Users are advised to upgrade to Apache Log4j API 2.25.5 or 2.26.1, both of which emit RFC 8259-compliant JSON for non-finite values. (CVE-2026-49844)

Note that Nessus relies on the presence of the package as reported by the vendor.

Solution

There is no known solution at this time.

See Also

https://access.redhat.com/security/cve/cve-2026-49844

https://security-tracker.debian.org/tracker/CVE-2026-49844

https://ubuntu.com/security/CVE-2026-49844

Plugin Details

Severity: Medium

ID: 326435

File Name: unpatched_CVE_2026_49844.nasl

Version: 1.7

Type: Local

Agent: unix

Family: Misc.

Published: 7/13/2026

Updated: 7/30/2026

Supported Sensors: Frictionless Assessment AWS, Frictionless Assessment Azure, Frictionless Assessment Agent, Nessus Agent, Agentless Assessment, Tenable Cloud Security, Tenable Self-Hosted Container Security, Nessus

Risk Information

VPR

Risk Factor: Low

Score: 3

Percentile: 23.72

CVSS v2

Risk Factor: Medium

Base Score: 5.4

Temporal Score: 4.6

Vector: CVSS2#AV:N/AC:H/Au:N/C:N/I:C/A:N

CVSS Score Source: CVE-2026-49844

CVSS v3

Risk Factor: Medium

Base Score: 5.9

Temporal Score: 5.4

Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N

Temporal Vector: CVSS:3.0/E:U/RL:U/RC:C

CVSS v4

Risk Factor: Medium

Base Score: 6.3

Threat Score: 1.7

Threat Vector: CVSS:4.0/E:U

Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N

Vulnerability Information

CPE: cpe:/o:canonical:ubuntu_linux:16.04:-:lts, cpe:/o:canonical:ubuntu_linux:18.04:-:lts, cpe:/o:canonical:ubuntu_linux:20.04:-:lts, cpe:/o:canonical:ubuntu_linux:22.04:-:lts, cpe:/o:canonical:ubuntu_linux:24.04:-:lts, cpe:/o:canonical:ubuntu_linux:26.04:-:lts, cpe:/o:centos:centos:8, cpe:/o:debian:debian_linux:11.0, cpe:/o:debian:debian_linux:12.0, cpe:/o:debian:debian_linux:13.0, cpe:/o:debian:debian_linux:14.0, cpe:/o:redhat:enterprise_linux:8, cpe:/o:redhat:enterprise_linux:9, p-cpe:/a:canonical:ubuntu_linux:apache-log4j2, p-cpe:/a:centos:centos:pki-resteasy-client, p-cpe:/a:centos:centos:pki-resteasy-core, p-cpe:/a:centos:centos:pki-resteasy-jackson2-provider, p-cpe:/a:centos:centos:pki-resteasy-servlet-initializer, p-cpe:/a:centos:centos:pki-resteasy, p-cpe:/a:centos:centos:resteasy-javadoc, p-cpe:/a:centos:centos:resteasy, p-cpe:/a:debian:debian_linux:apache-log4j2, p-cpe:/a:redhat:enterprise_linux:pki-resteasy-client, p-cpe:/a:redhat:enterprise_linux:pki-resteasy-core, p-cpe:/a:redhat:enterprise_linux:pki-resteasy-jackson2-provider, p-cpe:/a:redhat:enterprise_linux:pki-resteasy-servlet-initializer, p-cpe:/a:redhat:enterprise_linux:pki-resteasy, p-cpe:/a:redhat:enterprise_linux:resteasy-javadoc, p-cpe:/a:redhat:enterprise_linux:resteasy

Required KB Items: Host/local_checks_enabled, Host/cpu, global_settings/vendor_unpatched, Host/OS/identifier

Exploit Ease: No known exploits are available

Vulnerability Publication Date: 7/10/2026

Reference Information

CVE: CVE-2026-49844