PT-2026-30134 · Linux · Linux Kernel

Published 2026-04-03 · Updated 2026-04-25 · CVE-2026-23439

Positive Technologies (AI Summary)

CVSS v3.1

5.5

Medium

Base vector

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

Name of the Vulnerable Software and Affected Versions Linux kernel (affected versions not specified)

Description The Linux kernel contains a flaw in the udp tunnel functionality. When the IPv6 configuration (CONFIG IPV6) is disabled, the udp sock create6() function may return a success status without actually creating a socket. Subsequently, functions like fou create() attempt to dereference an uninitialized socket pointer, leading to a NULL pointer dereference. The crash was captured with a BUG message indicating a kernel NULL pointer dereference at fou nl add doit in net/ipv4/fou core.c. The patch resolves this by making udp sock create6() return -EPFNOSUPPORT when CONFIG IPV6 is disabled, ensuring callers handle the error appropriately. The issue is triggered only by privileged users.

Recommendations At the moment, there is no information about a newer version that contains a fix for this vulnerability.

NULL Pointer Dereference

Weakness Enumeration

CWE-476

Related Identifiers

CVE-2026-23439

ECHO-CE67-A7FA-8648

OESA-2026-2075

OESA-2026-2077

Affected Products

Linux Kernel

References · 30

• https://osv.dev/vulnerability/OESA-2026-2077 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-23171 · Security Note
• https://osv.dev/vulnerability/ROOT-OS-UBUNTU-2204-CVE-2026-23439 · Vendor Advisory
• https://ubuntu.com/security/CVE-2026-23439 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-23439 · Security Note
• https://nvd.nist.gov/vuln/detail/CVE-2026-31400 · Security Note
• https://git.kernel.org/stable/c/9f036aa0fe46c19e938f03d10e02c23f4fffae5e · Patch
• https://nvd.nist.gov/vuln/detail/CVE-2026-31426 · Security Note
• https://osv.dev/vulnerability/DEBIAN-CVE-2026-23439 · Vendor Advisory
• https://git.kernel.org/stable/c/ba7c9ddcdd077942b798979edb035207374d4096 · Patch
• https://security-tracker.debian.org/tracker/CVE-2026-23439 · Vendor Advisory
• https://osv.dev/vulnerability/BELL-CVE-2026-23439 · Vendor Advisory
• https://osv.dev/vulnerability/OESA-2026-2075 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-31403 · Security Note
• https://git.kernel.org/stable/c/a05a2149386f6dfb4245f522acdbef892acafc84 · Patch