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Linux Distros Unpatched Vulnerability : CVE-2026-9539

medium Nessus Plugin ID 322444

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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.

 - An out-of-bounds heap read and integer underflow in the TCP urgent data handling (sosendoob) in freedesktop.org libslirp version before v4.9.2 on hypervisor host environments (e.g., QEMU) allows a privileged guest VM attacker (root or CAP_NET_RAW) to leak gigabytes of sensitive host-process heap memory via sending crafted TCP segments with manipulated URG flags and urgent pointers (ti_urp). (CVE-2026-9539)

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://security-tracker.debian.org/tracker/CVE-2026-9539

https://ubuntu.com/security/CVE-2026-9539

Plugin Details

Severity: Medium

ID: 322444

File Name: unpatched_CVE_2026_9539.nasl

Version: 1.4

Type: Local

Agent: unix

Family: Misc.

Published: 6/24/2026

Updated: 7/13/2026

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

Risk Information

VPR

Risk Factor: Low

Score: 3.3

Percentile: 51.17

CVSS v2

Risk Factor: Medium

Base Score: 6.6

Temporal Score: 5.6

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

CVSS Score Source: CVE-2026-9539

CVSS v3

Risk Factor: Medium

Base Score: 6.5

Temporal Score: 6

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

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

Vulnerability Information

CPE: cpe:/o:debian:debian_linux:11.0, cpe:/o:canonical:ubuntu_linux:20.04:-:lts, cpe:/o:canonical:ubuntu_linux:22.04:-:lts, cpe:/o:debian:debian_linux:12.0, cpe:/o:canonical:ubuntu_linux:24.04:-:lts, p-cpe:/a:debian:debian_linux:libslirp, cpe:/o:canonical:ubuntu_linux:25.10, cpe:/o:canonical:ubuntu_linux:26.04:-:lts, p-cpe:/a:canonical:ubuntu_linux:libslirp

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

Exploit Ease: No known exploits are available

Vulnerability Publication Date: 6/24/2026

Reference Information

CVE: CVE-2026-9539