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Linux Distros Unpatched Vulnerability : CVE-2026-43050

medium Nessus Plugin ID 311576

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.

 - atm: lec: fix use-after-free in sock_def_readable() A race condition exists between lec_atm_close() setting priv->lecd to NULL and concurrent access to priv->lecd in send_to_lecd(), lec_handle_bridge(), and lec_atm_send(). When the socket is freed via RCU while another thread is still using it, a use-after-free occurs in sock_def_readable() when accessing the socket's wait queue. The root cause is that lec_atm_close() clears priv->lecd without any synchronization, while callers dereference priv->lecd without any protection against concurrent teardown. Fix this by converting priv->lecd to an RCU-protected pointer: - Mark priv->lecd as __rcu in lec.h - Use rcu_assign_pointer() in lec_atm_close() and lecd_attach() for safe pointer assignment - Use rcu_access_pointer() for NULL checks that do not dereference the pointer in lec_start_xmit(), lec_push(), send_to_lecd() and lecd_attach() - Use rcu_read_lock/rcu_dereference/rcu_read_unlock in send_to_lecd(), lec_handle_bridge() and lec_atm_send() to safely access lecd - Use rcu_assign_pointer() followed by synchronize_rcu() in lec_atm_close() to ensure all readers have completed before proceeding. This is safe since lec_atm_close() is called from vcc_release() which holds lock_sock(), a sleeping lock. - Remove the manual sk_receive_queue drain from lec_atm_close() since vcc_destroy_socket() already drains it after lec_atm_close() returns. v2: Switch from spinlock + sock_hold/put approach to RCU to properly fix the race. The v1 spinlock approach had two issues pointed out by Eric Dumazet: 1. priv->lecd was still accessed directly after releasing the lock instead of using a local copy. 2. The spinlock did not prevent packets being queued after lec_atm_close() drains sk_receive_queue since timer and workqueue paths bypass netif_stop_queue(). Note: Syzbot patch testing was attempted but the test VM terminated unexpectedly with Connection to localhost closed by remote host, likely due to a QEMU AHCI emulation issue unrelated to this fix. Compile testing with make W=1 net/atm/lec.o passes cleanly. (CVE-2026-43050)

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-2026-43050

https://security-tracker.debian.org/tracker/CVE-2026-43050

Plugin Details

Severity: Medium

ID: 311576

File Name: unpatched_CVE_2026_43050.nasl

Version: 1.2

Type: Local

Agent: unix

Family: Misc.

Published: 5/2/2026

Updated: 5/2/2026

Supported Sensors: Frictionless Assessment AWS, Frictionless Assessment Azure, Frictionless Assessment Agent, Nessus Agent, Agentless Assessment, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 6.7

CVSS v2

Risk Factor: Medium

Base Score: 6.9

Temporal Score: 5.9

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

CVSS Score Source: CVE-2026-43050

CVSS v3

Risk Factor: Medium

Base Score: 6.3

Temporal Score: 5.8

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

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

Vulnerability Information

CPE: p-cpe:/a:centos:centos:kernel-headers, p-cpe:/a:centos:centos:kernel-rt-modules-internal, p-cpe:/a:centos:centos:kernel-rt-64k-modules-partner, p-cpe:/a:redhat:enterprise_linux:kernel-debug-devel, p-cpe:/a:redhat:enterprise_linux:kernel-zfcpdump-modules, p-cpe:/a:centos:centos:kernel-64k-modules-extra, p-cpe:/a:redhat:enterprise_linux:kernel-modules, p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug-devel-matched, p-cpe:/a:redhat:enterprise_linux:kernel-tools, p-cpe:/a:redhat:enterprise_linux:kernel-debug-modules, p-cpe:/a:centos:centos:rtla, cpe:/o:debian:debian_linux:11.0, p-cpe:/a:centos:centos:python-perf, p-cpe:/a:centos:centos:kernel-rt-devel, p-cpe:/a:redhat:enterprise_linux:kernel-rt-modules-core, p-cpe:/a:centos:centos:kernel-64k-debug-modules-internal, p-cpe:/a:centos:centos:kernel-rt-selftests-internal, p-cpe:/a:centos:centos:kernel-rt-debug-devel-matched, p-cpe:/a:centos:centos:kernel-64k, p-cpe:/a:centos:centos:kernel-debug-modules-core, p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug, p-cpe:/a:redhat:enterprise_linux:kernel-rt-64k-modules, p-cpe:/a:centos:centos:kernel-kdump, p-cpe:/a:centos:centos:kernel-64k-debug-devel, cpe:/o:centos:centos:8, p-cpe:/a:centos:centos:kernel-zfcpdump-modules-internal, p-cpe:/a:centos:centos:kernel-64k-debug-modules-core, p-cpe:/a:centos:centos:libperf, p-cpe:/a:redhat:enterprise_linux:bpftool, p-cpe:/a:centos:centos:kernel-zfcpdump-modules-core, p-cpe:/a:redhat:enterprise_linux:kernel-rt-64k-debug-modules-extra, p-cpe:/a:redhat:enterprise_linux:kernel-debug-modules-core, p-cpe:/a:centos:centos:kernel-rt-64k-debug-modules-internal, p-cpe:/a:centos:centos:bpftool, p-cpe:/a:centos:centos:kernel-core, p-cpe:/a:redhat:enterprise_linux:kernel-rt-selftests-internal, p-cpe:/a:redhat:enterprise_linux:kernel-modules-partner, p-cpe:/a:centos:centos:kernel-64k-debug-core, p-cpe:/a:redhat:enterprise_linux:kernel-rt-64k-debug, p-cpe:/a:centos:centos:kernel-64k-modules-internal, p-cpe:/a:redhat:enterprise_linux:kernel-debug, p-cpe:/a:centos:centos:kernel-kdump-devel, p-cpe:/a:centos:centos:kernel-rt-64k-modules, p-cpe:/a:centos:centos:kernel-64k-debug, p-cpe:/a:debian:debian_linux:linux, p-cpe:/a:redhat:enterprise_linux:kernel-rt-modules, p-cpe:/a:centos:centos:kernel-rt-64k-debug-core, p-cpe:/a:redhat:enterprise_linux:kernel-64k-debug-modules-core, p-cpe:/a:centos:centos:rv, p-cpe:/a:redhat:enterprise_linux:kernel-rt-64k, p-cpe:/a:redhat:enterprise_linux:kernel-rt-core, p-cpe:/a:centos:centos:kernel-rt-64k-debug-kvm, p-cpe:/a:centos:centos:kernel-64k-debug-modules-extra, p-cpe:/a:centos:centos:kernel-tools-libs, p-cpe:/a:redhat:enterprise_linux:kernel-64k, p-cpe:/a:redhat:enterprise_linux:rtla, p-cpe:/a:redhat:enterprise_linux:kernel, p-cpe:/a:redhat:enterprise_linux:kernel-zfcpdump-modules-internal, p-cpe:/a:centos:centos:kernel-modules-extra, p-cpe:/a:centos:centos:kernel-cross-headers, p-cpe:/a:redhat:enterprise_linux:kernel-uki-virt-addons, p-cpe:/a:centos:centos:kernel-doc, p-cpe:/a:centos:centos:kernel-debug-modules, p-cpe:/a:redhat:enterprise_linux:kernel-ipaclones-internal, p-cpe:/a:centos:centos:kernel-rt-debug-kvm, p-cpe:/a:centos:centos:kernel-rt-debug-devel, p-cpe:/a:redhat:enterprise_linux:python-perf, p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug-modules-internal, cpe:/o:centos:centos:7, p-cpe:/a:redhat:enterprise_linux:kernel-64k-modules-partner, p-cpe:/a:redhat:enterprise_linux:kernel-rt-64k-core, p-cpe:/a:redhat:enterprise_linux:kernel-rt-64k-modules-internal, p-cpe:/a:centos:centos:kernel-rt-core, p-cpe:/a:centos:centos:kernel-rt-doc, p-cpe:/a:redhat:enterprise_linux:kernel-devel, p-cpe:/a:redhat:enterprise_linux:kernel-rt-64k-devel-matched, p-cpe:/a:redhat:enterprise_linux:kernel-rt-64k-debug-devel, p-cpe:/a:redhat:enterprise_linux:kernel-rt-64k-kvm, p-cpe:/a:centos:centos:kernel-rt-kvm, p-cpe:/a:redhat:enterprise_linux:kernel-kdump, p-cpe:/a:redhat:enterprise_linux:kernel-rt-modules-extra, p-cpe:/a:centos:centos:kernel-rt-64k-debug-devel, p-cpe:/a:redhat:enterprise_linux:kernel-rt, p-cpe:/a:redhat:enterprise_linux:kernel-zfcpdump, p-cpe:/a:redhat:enterprise_linux:kernel-rt-64k-modules-partner, p-cpe:/a:centos:centos:kernel-64k-devel-matched, p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug-modules-extra, p-cpe:/a:redhat:enterprise_linux:kernel-rt-trace-devel, p-cpe:/a:centos:centos:kernel-zfcpdump-devel, p-cpe:/a:redhat:enterprise_linux:kernel-64k-modules-core, cpe:/o:redhat:enterprise_linux:8, p-cpe:/a:redhat:enterprise_linux:kernel-rt-modules-internal, p-cpe:/a:centos:centos:kernel-rt-debug-modules, p-cpe:/a:centos:centos:kernel-uki-virt, p-cpe:/a:centos:centos:kernel-rt-devel-matched, p-cpe:/a:centos:centos:kernel-debug-uki-virt-addons, p-cpe:/a:centos:centos:kernel-zfcpdump, p-cpe:/a:redhat:enterprise_linux:kernel-abi-whitelists, p-cpe:/a:redhat:enterprise_linux:python3-perf, p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug-devel, p-cpe:/a:centos:centos:kernel-rt-64k-debug-devel-matched, p-cpe:/a:redhat:enterprise_linux:kernel-64k-debug-modules-extra, p-cpe:/a:redhat:enterprise_linux:kernel-rt-doc, p-cpe:/a:centos:centos:kernel-debug-devel-matched, p-cpe:/a:redhat:enterprise_linux:perf, p-cpe:/a:redhat:enterprise_linux:kernel-abi-stablelists, p-cpe:/a:centos:centos:kernel-rt-modules, p-cpe:/a:centos:centos:kernel-tools, p-cpe:/a:centos:centos:kernel-abi-stablelists, p-cpe:/a:redhat:enterprise_linux:kernel-debug-core, p-cpe:/a:redhat:enterprise_linux:kernel-zfcpdump-modules-partner, p-cpe:/a:redhat:enterprise_linux:kernel-rt-64k-modules-extra, cpe:/o:redhat:enterprise_linux:7, p-cpe:/a:centos:centos:kernel-zfcpdump-devel-matched, p-cpe:/a:redhat:enterprise_linux:kernel-uki-virt, p-cpe:/a:redhat:enterprise_linux:libperf, p-cpe:/a:redhat:enterprise_linux:kernel-devel-matched, p-cpe:/a:centos:centos:kernel-debug-devel, p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug-kvm, p-cpe:/a:redhat:enterprise_linux:kernel-tools-libs, p-cpe:/a:centos:centos:kernel-rt-64k-debug-modules-partner, p-cpe:/a:centos:centos:kernel-rt-debug, p-cpe:/a:centos:centos:kernel-64k-debug-modules, p-cpe:/a:centos:centos:kernel-modules, p-cpe:/a:redhat:enterprise_linux:kernel-modules-internal, p-cpe:/a:centos:centos:kernel-devel, p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug-modules, p-cpe:/a:centos:centos:kernel-rt-64k-modules-internal, p-cpe:/a:centos:centos:kernel-rt-trace-kvm, p-cpe:/a:redhat:enterprise_linux:kernel-cross-headers, p-cpe:/a:centos:centos:kernel-rt-64k-debug-modules-extra, p-cpe:/a:centos:centos:kernel-tools-libs-devel, p-cpe:/a:centos:centos:kernel-64k-core, p-cpe:/a:redhat:enterprise_linux:kernel-zfcpdump-devel-matched, p-cpe:/a:centos:centos:kernel-debug-uki-virt, p-cpe:/a:centos:centos:kernel-selftests-internal, p-cpe:/a:centos:centos:kernel-rt-64k-debug, p-cpe:/a:centos:centos:perf, p-cpe:/a:redhat:enterprise_linux:kernel-modules-extra, p-cpe:/a:redhat:enterprise_linux:kernel-modules-core, p-cpe:/a:centos:centos:kernel-modules-partner, p-cpe:/a:redhat:enterprise_linux:libperf-devel, p-cpe:/a:redhat:enterprise_linux:kernel-rt-64k-debug-devel-matched, p-cpe:/a:centos:centos:kernel-zfcpdump-core, p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug-core, p-cpe:/a:centos:centos:libperf-devel, p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug-modules-partner, p-cpe:/a:redhat:enterprise_linux:kernel-rt-64k-debug-kvm, p-cpe:/a:redhat:enterprise_linux:kernel-64k-debug-core, cpe:/o:redhat:enterprise_linux:9, p-cpe:/a:redhat:enterprise_linux:kernel-core, p-cpe:/a:centos:centos:kernel-rt-debug-modules-extra, p-cpe:/a:centos:centos:kernel-zfcpdump-modules, p-cpe:/a:centos:centos:kernel-rt-debug-modules-internal, p-cpe:/a:redhat:enterprise_linux:kernel-rt-trace-kvm, p-cpe:/a:centos:centos:kernel-rt-64k-kvm, p-cpe:/a:redhat:enterprise_linux:kernel-64k-debug-devel-matched, p-cpe:/a:centos:centos:kernel-64k-modules-core, p-cpe:/a:centos:centos:kernel-64k-modules-partner, p-cpe:/a:centos:centos:kernel-64k-modules, p-cpe:/a:redhat:enterprise_linux:kernel-headers, p-cpe:/a:redhat:enterprise_linux:kernel-debug-devel-matched, p-cpe:/a:centos:centos:kernel-rt-64k-devel, p-cpe:/a:redhat:enterprise_linux:kernel-64k-debug-modules-partner, p-cpe:/a:centos:centos:kernel-rt-trace-devel, p-cpe:/a:centos:centos:kernel-rt-modules-extra, p-cpe:/a:centos:centos:kernel-bootwrapper, p-cpe:/a:centos:centos:kernel-64k-debug-modules-partner, p-cpe:/a:redhat:enterprise_linux:kernel-rt-devel-matched, p-cpe:/a:redhat:enterprise_linux:kernel-tools-libs-devel, p-cpe:/a:centos:centos:kernel-rt-64k-modules-core, p-cpe:/a:redhat:enterprise_linux:rv, p-cpe:/a:centos:centos:kernel-debug, p-cpe:/a:centos:centos:kernel, p-cpe:/a:centos:centos:kernel-zfcpdump-modules-partner, p-cpe:/a:centos:centos:kernel-64k-devel, p-cpe:/a:centos:centos:kernel-rt-trace, p-cpe:/a:redhat:enterprise_linux:kernel-rt-64k-debug-core, p-cpe:/a:redhat:enterprise_linux:kernel-kdump-devel, p-cpe:/a:redhat:enterprise_linux:kernel-debug-uki-virt-addons, p-cpe:/a:redhat:enterprise_linux:kernel-selftests-internal, p-cpe:/a:centos:centos:kernel-rt-64k-devel-matched, p-cpe:/a:centos:centos:kernel-rt-modules-core, p-cpe:/a:redhat:enterprise_linux:kernel-rt-64k-debug-modules-partner, p-cpe:/a:centos:centos:kernel-debug-core, p-cpe:/a:centos:centos:kernel-rt-64k-debug-modules-core, p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug-modules-core, p-cpe:/a:redhat:enterprise_linux:kernel-64k-debug-modules, p-cpe:/a:redhat:enterprise_linux:kernel-rt-64k-debug-modules-core, p-cpe:/a:centos:centos:kernel-rt-debug-core, p-cpe:/a:centos:centos:kernel-rt-64k, p-cpe:/a:redhat:enterprise_linux:kernel-debug-modules-extra, p-cpe:/a:redhat:enterprise_linux:kernel-rt-kvm, p-cpe:/a:redhat:enterprise_linux:kernel-debug-uki-virt, p-cpe:/a:centos:centos:kernel-modules-core, p-cpe:/a:redhat:enterprise_linux:kernel-64k-devel, p-cpe:/a:redhat:enterprise_linux:kernel-rt-64k-debug-modules, p-cpe:/a:redhat:enterprise_linux:kernel-zfcpdump-modules-extra, p-cpe:/a:redhat:enterprise_linux:kernel-bootwrapper, p-cpe:/a:redhat:enterprise_linux:kernel-64k-core, p-cpe:/a:redhat:enterprise_linux:kernel-rt-64k-modules-core, p-cpe:/a:centos:centos:kernel-ipaclones-internal, p-cpe:/a:centos:centos:kernel-uki-virt-addons, p-cpe:/a:redhat:enterprise_linux:kernel-64k-debug-modules-internal, p-cpe:/a:centos:centos:kernel-rt-64k-core, p-cpe:/a:centos:centos:kernel-abi-whitelists, p-cpe:/a:redhat:enterprise_linux:kernel-rt-trace, p-cpe:/a:centos:centos:kernel-debug-modules-partner, p-cpe:/a:centos:centos:kernel-debug-modules-extra, p-cpe:/a:centos:centos:kernel-devel-matched, p-cpe:/a:redhat:enterprise_linux:kernel-64k-debug-devel, p-cpe:/a:redhat:enterprise_linux:kernel-zfcpdump-modules-core, p-cpe:/a:redhat:enterprise_linux:kernel-64k-modules-extra, p-cpe:/a:redhat:enterprise_linux:kernel-64k-debug, p-cpe:/a:centos:centos:kernel-64k-debug-devel-matched, p-cpe:/a:redhat:enterprise_linux:kernel-64k-modules-internal, p-cpe:/a:redhat:enterprise_linux:kernel-zfcpdump-devel, p-cpe:/a:centos:centos:kernel-rt-debug-modules-partner, p-cpe:/a:redhat:enterprise_linux:kernel-64k-devel-matched, p-cpe:/a:redhat:enterprise_linux:kernel-debug-modules-partner, p-cpe:/a:centos:centos:kernel-zfcpdump-modules-extra, p-cpe:/a:redhat:enterprise_linux:kernel-doc, p-cpe:/a:centos:centos:kernel-debug-modules-internal, p-cpe:/a:centos:centos:kernel-rt-debug-modules-core, p-cpe:/a:redhat:enterprise_linux:kernel-zfcpdump-core, p-cpe:/a:redhat:enterprise_linux:kernel-rt-devel, p-cpe:/a:redhat:enterprise_linux:kernel-rt-modules-partner, p-cpe:/a:centos:centos:kernel-rt-modules-partner, p-cpe:/a:centos:centos:kernel-rt-64k-debug-modules, p-cpe:/a:centos:centos:kernel-modules-internal, p-cpe:/a:redhat:enterprise_linux:kernel-64k-modules, p-cpe:/a:redhat:enterprise_linux:kernel-rt-64k-devel, p-cpe:/a:centos:centos:kernel-rt, p-cpe:/a:centos:centos:python3-perf, p-cpe:/a:redhat:enterprise_linux:kernel-debug-modules-internal, p-cpe:/a:redhat:enterprise_linux:kernel-rt-64k-debug-modules-internal, p-cpe:/a:centos:centos:kernel-rt-64k-modules-extra

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: 5/1/2026

Reference Information

CVE: CVE-2026-43050