CVE intelligence

CVE-2026-72020

Vulnerability intelligence

Published Aug 15, 2026Sources checked Nov 10, 2026

9.8CRITICALCVSS out of 10

What this means

Review the available evidence

CVE-2026-72020 and is rated Critical severity with a CVSS score of 9.8. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.

What to do next

Remediation and response

Ubuntu Security Notices guidance

Vendor revision: Oct 2, 2026

Vendor remediation details

This update corrects flaws in the following subsystems: - ARM64 architecture; - S390 architecture; - x86 architecture; - DRBD Distributed Replicated Block Device drivers; - InfiniBand drivers; - IOMMU subsystem; - Multiple devices driver; - Network drivers; - Microsoft Azure Network Adapter (MANA) driver; - NVME drivers; - TCM subsystem; - Virtio Host (VHOST) subsystem; - Xen hypervisor drivers; - AFS file system; - File systems infrastructure; - Network file systems library; - Network file system (NFS) client; - NTFS3 file system; - OCFS2 file system; - OrangeFS file system; - SMB network file system; - IPv4 networking; - Sun RPC protocol; - IPv6 networking; - IP tunnels definitions; - Netfilter; - TCP network protocol; - Locking primitives; - 9P file system network protocol; - B.A.T.M.A.

Ubuntu Security Notices guidance

Vendor revision: Sep 30, 2026

Vendor remediation details

Ubuntu Security Notices guidance

Vendor revision: Sep 29, 2026

Vendor remediation details

CISA KEVNot listedBased on the latest collected catalog

EPSS0.7%Estimated 30-day exploitation probability

Ransomware useNot markedCISA KEV ransomware field

Threat actors0Source-linked actor relationships

Overview

What is CVE-2026-72020?

In the Linux kernel, the following vulnerability has been resolved:

ipvs: reset full ip_vs_seq structs in ip_vs_conn_new

Commit 9a05475cebdd ("ipvs: avoid kmem_cache_zalloc in ip_vs_conn_new") changed ip_vs_conn_new() to allocate an ip_vs_conn object with kmem_cache_alloc(). The function then initializes many fields explicitly, but only resets in_seq.delta and out_seq.delta in the two struct ip_vs_seq members.

That leaves init_seq and previous_delta uninitialized. This is normally harmless while the corresponding IP_VS_CONN_F_IN_SEQ or IP_VS_CONN_F_OUT_SEQ flag is clear.

For connections learned from a sync message, however, ip_vs_proc_conn() preserves those flags from IP_VS_CONN_F_BACKUP_MASK and passes opt=NULL when the message omits IPVS_OPT_SEQ_DATA. In that case the new connection can be hashed with SEQ flags set but with the rest of in_seq/out_seq still containing stale slab data.

When a packet for such a connection is later handled by an IPVS application helper, vs_fix_seq() and vs_fix_ack_seq() use previous_delta and init_seq to rewrite TCP sequence numbers. A malformed sync message can therefore make forwarded packets carry stale slab bytes in their TCP seq/ack numbers, and can also corrupt the forwarded TCP flow.

Reset both struct ip_vs_seq members completely before publishing the connection. This matches the existing "reset struct ip_vs_seq" comment and keeps the sequence-adjustment gates inactive unless valid sequence data is installed later.

Source: NVD