Linux Distros Unpatched Vulnerability : CVE-2026-98503

critical Nessus Plugin ID 367103

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.

- packet: use ubuf_info completion for TX_RING packets tpacket_snd sends skbs with frags pointing into its ring slots. Slots are released when skb->destructor is called. A call to skb_orphan calls skb->destructor before the skb is freed. This can cause the slot to be reused while still linked into the skb. Switch to standard zerocopy completion (ubuf_info) so the slot is only released once all references to the payload are freed or copied. Restore skb->destructor to standard sock_wfree. The ubuf_info completion callback can be called with a NULL skb, but only from net_zcopy_put and related API, used by zerocopy implementations that hold their own reference on the uarg, such as MSG_ZEROCOPY. This uarg is only ever completed from skb_zcopy_clear, so skb is always set. To prevent userspace from aliasing in-flight state on shared ring slots, allocate tpacket_uarg per packet, rather than per slot. This adds a small allocation to the transmit path. Use standard kmalloc to allow backporting to stable kernels. The uarg holds an sk_wmem_alloc reference, rather than an sk_refcnt reference. packet_free_tx_ring waits on sk_wmem_alloc before freeing the ring pages. Always allocate vec->deferred for tx_ring so page-backed rings also wait on sk_wmem_alloc when skb_copy_ubufs drops page refs before calling tpacket_ubuf_complete. Drop the tx_ring.pg_vec test that tpacket_destruct_skb performed before accessing the slot. The sk_wmem_alloc reference now guarantees that the slot is valid. The test is also not sufficient by itself, as it reads pg_vec without pg_vec_lock, so it can race with packet_set_ring. As a result a slot is released when its payload is copied, which can be before transmission (e.g., in skb_orphan_frags_rx). If copied before skb_tx_timestamp() is called, no slot timestamp is recorded, similar to when skb_orphan() was called early in the datapath before this patch. Revert the now unused previous skb_zcopy_.._nouarg infra. Depends on commit 992cc9f94ca9 (net/packet: defer vmalloc TX_RING free until skbs finish). (CVE-2026-98503)

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

Solution

There is no known solution at this time.

Plugin Details

Severity: Critical

ID: 367103

File Name: unpatched_CVE_2026_98503.nasl

Version: 1.1

Type: Local

Agent: unix

Family: Misc.

Published: 10/18/2026

Updated: 10/18/2026

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

Risk Information

VPR

Risk Factor: Medium

Score: 5

Percentile: 93.03

CVSS v2

Risk Factor: High

Base Score: 7.5

Temporal Score: 6.4

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

CVSS Score Source: CVE-2026-98503

CVSS v3

Risk Factor: Critical

Base Score: 9.8

Temporal Score: 9

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

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

Vulnerability Information

CPE: cpe:/o:debian:debian_linux:12.0, p-cpe:/a:debian:debian_linux:linux

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: 10/18/2026

Reference Information

CVE: CVE-2026-98503

Detections

Analytics